Crosslinked rubber article and solid composition

Abstract

Provided is a crosslinked rubber article which contains a crosslinked rubber containing a constituent unit based on tetrafluoroethylene, and has a total content of 10,000 ppb by mass or less of a compound (B), a content of 1,000 ppb by mass or less of a compound (S1), and a content of 1,000 ppm by mass or less of a compound (S11). The compound (B) is a compound which has a CF2 group and an ionic functional group, in which the number of CF2 groups per ionic functional group is 30 or less, which does not have a carbon-carbon double bond or a carbon-carbon triple bond, and which has a number average molecular weight of 3,000 or less. M1 is a hydrogen atom, Na, K, or NH4; X111 and X112 are each a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms; p1 is an integer of 3-13; and q11 and r11 are each an integer of 0 or more.　(S1): H(CF2)p1COOM1, (S11): CF3(OCFX111)q11(OCFX112)r11OCF3

Description

Crosslinked rubber articles and solid compositions

[0001] This disclosure relates to crosslinked rubber articles and solid compositions.

[0002] Crosslinked rubber articles, which contain crosslinked rubber that is a crosslinked body of fluorine-containing elastomer, are used in various industrial fields because they have excellent heat resistance, chemical resistance, flame retardancy, weather resistance, etc.

[0003] For example, Patent Document 1 describes a crosslinked rubber article obtained by crosslinking a fluorine-containing elastomer, which is obtained by emulsion polymerization of a fluorine-containing monomer using an emulsifier containing a fluorine atom, in the presence of a crosslinking agent.

[0004] International Publication No. 2010 / 082633

[0005] When a fluorine-containing elastomer manufactured using an emulsifier containing fluorine atoms is crosslinked, for example, a crosslinked rubber article is obtained that contains not only the crosslinked rubber, which is the crosslinked body of the fluorine-containing elastomer, but also the emulsifier containing fluorine atoms used in the manufacture of the fluorine-containing elastomer. However, in crosslinked rubber articles containing a large amount of emulsifier containing fluorine atoms, when compressed, the remaining emulsifier containing fluorine atoms may function as a plasticizer, making it difficult for the article to recover its shape upon release.

[0006] This disclosure has been made in view of these circumstances, and one embodiment of this disclosure aims to solve the problem of providing a crosslinked rubber article with low compression set and a solid composition from which such a crosslinked rubber article can be obtained.

[0007] This disclosure includes the following aspects. <1> A crosslinked rubber article containing a crosslinked rubber containing a structural unit based on tetrafluoroethylene, wherein the crosslinked rubber article does not contain any of the compounds represented by formula (S1), formula (S2), formula (S3), formula (S4), formula (S5), formula (S6), formula (S7), formula (S8), formula (S9), and formula (S10), or contains at least one selected from the group consisting of the compounds (S1) to (S10) and the total content of the compounds (S1) to (S10) is 10,000 mass ppb or less with respect to the crosslinked rubber article, does not contain the compound (S1), or contains the compound (S1) and the total content of the compound (S1) is 1,000 mass ppb or less with respect to the crosslinked rubber article, does not contain the compound represented by formula (S11), or contains the compound (S11) and the total content of the compound (S11) is 1,000 mass ppb or less with respect to the crosslinked rubber article. Crosslinked rubber article. H(CF ２ , ５ , ５２ , ２ , ｐ６ , ６１ , ２ , ｑ５ ) ｐ１ COOM １ (S1) H(CF ２ ) ｐ２ SO ３ M ２ (S2) F(CF ２ ) ｐ３ COOM ３ (S3) F(CF ２ ) ｐ４ SO ３ M ４ (S4) X ５１ (CF<​​​​​​​​​​​​​​​​​​​​​​​６２ ) CF(X ６３ )) ｑ６ OCF(X ６４ ) COOM ６ (S6) X ７１ (CF ２ ) ｐ７ CF(X ７２ ) (OCF(X ７３ ) CF(X ７４ )) ｑ７ OCF(X ７５ ) COOM ７ (S7)

[0008]

[0009] X １０１ CF ２ (OCF ２ CF ２ ) ｑ１０ (OCF ２ ) ｒ１０ X １０２ (S10) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formulas (S1) to (S11), M １ ~M ９ Each is independently a hydrogen atom, Na, K, or NH ４ X ５１ , X ６１ , X ７１ , X ８１ , X ８２ , X ９１ , and X ９２ Each of these is independently a hydrogen atom, a fluorine atom, or a chlorine atom, and X １０１ and X １０２ Each of these is independently a hydrogen atom, a fluorine atom, a COOH group, or a chlorine atom, and X １０１ and X １０２ At least one of them is COOH, X ５２ , X ６２ ~X ６４ , and X ７２ ~X ７５ Each of these is independently a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms, and Rf ８~Rf ９ Each of these is independently a fluorine-containing alkylene group having 1 to 20 carbon atoms, and X １１１ and X １１２ Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 and p3 are independently integers from 3 to 13, p2 and p4 are independently integers from 4 to 10, p5 to p7 are independently integers from 1 to 10, q5 to q7 are independently integers from 0 to 3, q8 to q9 are independently integers from 1 to 20, n8 to n9 are independently integers from 1 to 30, and q8 and n8 are the CF contained in compound (S8). ２ A combination of integers such that the number of elements is 30 or less, where q9 and n9 are the CFs of the compound (S9). ２ A combination of integers such that the number of units is 30 or less, where q10, r10, q11, and r11 are each independently integers of 0 or more, where q10 and r10 are a combination of integers such that the number average molecular weight of compound (S10) is 300 to 2000, and q11 and r11 are a combination of integers such that the number average molecular weight of compound (S11) is 300 to 2000. <2> A crosslinked rubber article containing a crosslinked rubber comprising a constituent unit based on tetrafluoroethylene, wherein 1 or more CF ２ It has a group and one or more ionic functional groups, wherein the ionic functional groups are COOM, SO ３ M, PO ４ M, or SO ４ M is a hydrogen atom, Na, K, or NH ４ The CF per ionic functional group ２When a compound having 30 or less basic groups, no carbon-carbon double bond and no carbon-carbon triple bond, and a number average molecular weight of 3000 or less is used as compound (B), the crosslinked rubber article does not contain compound (B), or contains compound (B) and the total content of compound (B) is 10,000 mass ppb or less based on the crosslinked rubber article, does not contain compound (S1) represented by formula (S1) among compound (B), or contains compound (S1) and the total content of compound (S1) is 1,000 mass ppb or less based on the crosslinked rubber article, and does not contain compound (S11) represented by formula (S11) which is a compound other than compound (B), or contains compound (S11) and the total content of compound (S11) is 1,000 mass ppm or less based on the crosslinked rubber article. Crosslinked rubber article. H(CF ２ ) ｐ１ COOM １ (S1) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formula (S1) and (S11), M １ is a hydrogen atom, Na, K, or NH ４ , and X １１１ and X １１２Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 is an integer from 3 to 13, q11 and r11 are independently integers of 0 or more, and q11 and r11 are a combination of integers such that the number average molecular weight of compound (S11) is 300 to 2000. <3> The crosslinked rubber article according to <1> or <2>, wherein the crosslinked rubber article does not contain compound (S1), or contains compound (S1) and the total content of compound (S1) is less than 100 ppb by mass relative to the crosslinked rubber article. <4> The crosslinked rubber article according to any one of <1> to <3>, wherein the crosslinked rubber further comprises a constituent unit based on at least one selected from the group consisting of perfluoro(alkyl vinyl ether), propylene, vinylidene fluoride, and hexafluoropropylene. <5> The crosslinked rubber article according to any one of <1> to <3>, wherein the crosslinked rubber further comprises a perfluoro(alkyl vinyl ether) based structural unit. <6> The crosslinked rubber article according to any one of <1> to <5>, wherein the crosslinked rubber has a crosslinked structure derived from a hydrocarbon group. <7> The crosslinked rubber article according to any one of <1> to <5>, wherein the crosslinked rubber has a crosslinked structure derived from a heterocycle. <8> The crosslinked rubber article according to any one of <1> to <7>, wherein the total content of metal elements is 50 ppm by mass or less with respect to the crosslinked rubber article. <9> The crosslinked rubber article according to any one of <1> to <8>, used as a component for semiconductor manufacturing equipment.<10> A solid composition containing a fluorine-containing elastomer having a structural unit based on tetrafluoroethylene and at least one selected from the group consisting of a bromine atom, an iodine atom, and a cyano group, wherein the solid composition does not contain any of the compounds represented by formula (S1), formula (S2), formula (S3), formula (S4), formula (S5), formula (S6), formula (S7), formula (S8), formula (S9), and formula (S10), or contains at least one selected from the group consisting of the compounds (S1) to (S10), and the total content of the compounds (S1) to (S10) is 10,000 ppb by mass or less relative to the solid composition. A solid composition that does not contain the compound (S1), or contains the compound (S1) and the total content of the compound (S1) is 1000 ppb by mass or less relative to the solid composition, and does not contain the compound (S11) represented by formula (S11), or contains the compound (S11) and the total content of the compound (S11) is 1000 ppb by mass or less relative to the solid composition. H(CF. ２ ) ｐ１ COOM １ (S1) H(CF ２ ) ｐ２ SO ３ M ２ (S2) F(CF) ２ ) ｐ３ COOM ３ (S3) F(CF) ２ ) ｐ４ SO ３ M ４ (S4) X ５１ (CF ２ ) ｐ５ (OCF ２ CF ２ CF ２ ) ｑ５ OCF(X ５２ ) CF ２ COOM ５ (S5) X ６１ (CF２ ) ｐ６ (OCF(X ６２ ) CF(X ６３ )) ｑ６ OCF(X ６４ ) COOM ６ (S6) X ７１ (CF ２ ) ｐ７ CF(X ７２ ) (OCF(X ７３ ) CF(X ７４ )) ｑ７ OCF(X ７５ ) COOM ７ (S7) X １０１ CF ２ (OCF ２ CF ２ ) ｑ１０ (OCF ２ ) ｒ１０ X １０２ (S10) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formulas (S1) to (S11), M １ ~M ９ Each is independently a hydrogen atom, Na, K, or NH ４ X ５１ , X ６１ , X ７１ , X ８１ , X ８２ , X ９１ , and X ９２ Each of these is independently a hydrogen atom, a fluorine atom, or a chlorine atom, and X １０１ and X １０２ Each of these is independently a hydrogen atom, a fluorine atom, a COOH group, or a chlorine atom, and X １０１ and X １０２ At least one of them is COOH, X ５２ , X ６２ ~X ６４ , and X ７２ ~X ７５ Each of these is independently a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms, and Rf ８ ~Rf ９Each of these is independently a fluorine-containing alkylene group having 1 to 20 carbon atoms, and X １１１ and X １１２ Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 and p3 are independently integers from 3 to 13, p2 and p4 are independently integers from 4 to 10, p5 to p7 are independently integers from 1 to 10, q5 to q7 are independently integers from 0 to 3, q8 to q9 are independently integers from 1 to 20, n8 to n9 are independently integers from 1 to 30, and q8 and n8 are the CF contained in compound (S8). ２ A combination of integers such that the number of elements is 30 or less, where q9 and n9 are the CFs of the compound (S9). ２ A combination of integers such that the number of groups is 30 or less, where q10, r10, q11, and r11 are each independently integers of 0 or more, where q10 and r10 are a combination of integers such that the number average molecular weight of compound (S10) is 300 to 2000, and q11 and r11 are a combination of integers such that the number average molecular weight of compound (S11) is 300 to 2000. <11> A solid composition containing a fluorine-containing elastomer having a constituent unit based on tetrafluoroethylene and at least one selected from the group consisting of a bromine atom, an iodine atom, and a cyano group, wherein 1 or more CF ２ It has a group and one or more ionic functional groups, wherein the ionic functional groups are COOM, SO ３ M, PO ４ M, or SO ４ M is a hydrogen atom, Na, K, or NH ４ The CF per ionic functional group ２When compound (B) is defined as a compound having 30 or fewer groups, lacking carbon-carbon double bonds and carbon-carbon triple bonds, and having a number-average molecular weight of 3000 or less, the solid composition either does not contain compound (B), or contains compound (B) with a total content of compound (B) of 10000 ppb by mass or less relative to the solid composition, either does not contain compound (S1) represented by formula (S1) among the compounds (B), or contains compound (S1) with a total content of compound (S1) of 1000 ppb by mass or less relative to the solid composition, and does not contain compound (S11) represented by formula (S11), which is a compound other than compound (B), or contains compound (S11) with a total content of compound (S11) of 1000 ppm by mass or less relative to the solid composition. ２ ) ｐ１ COOM １ (S1) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In equations (S1) and (S11), M １ is a hydrogen atom, Na, K, or NH ４ X １１１ and X １１２ Each of the following is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms; p1 is an integer from 3 to 13; q11 and r11 are independently integers of 0 or more; and q11 and r11 are a combination of integers such that the number-average molecular weight of the compound (S11) is between 300 and 2000.

[0010] According to one embodiment of the present invention, a crosslinked rubber article with low compression set and a solid composition for obtaining the crosslinked rubber article are provided.

[0011] In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit of that range may be replaced by the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. If multiple types of the substance corresponding to each component are present in the composition, the content of each component means the total content of the multiple types of substances present in the composition unless otherwise specified. In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition unless otherwise specified. In this disclosure, "elastomer" refers to a non-melting, elastic, fluorine-containing polymer exhibiting a storage modulus G' of 80 kPa or higher at 100°C and a frequency of 50 cpm, as measured in accordance with ASTM D6204, and is distinct from fluororesins. In this disclosure, the number-average molecular weight (Mn) is a value measured by gel permeation chromatography (GPC) using polystyrene as a standard substance.

[0012] [Crosslinked Rubber Article] <First Embodiment> The crosslinked rubber article according to the first embodiment of the present disclosure (hereinafter also referred to as "crosslinked rubber article A") contains crosslinked rubber containing a constituent unit based on tetrafluoroethylene, and does not contain any of the compounds represented by formula (S1), formula (S2), formula (S3), formula (S4), formula (S5), formula (S6), formula (S7), formula (S8), formula (S9), and formula (S10), or contains at least one selected from the group consisting of compounds (S1) to (S10), and the total content of compounds (S1) to (S10) is 10,000 ppb by mass or less relative to the crosslinked rubber article. Either the compound (S1) is not contained, or the compound (S1) is contained and the total content of compound (S1) is 1000 ppb by mass or less relative to the crosslinked rubber article, and either the compound (S11) represented by formula (S11) is not contained, or the compound (S11) is contained and the total content of compound (S11) is 1000 ppb by mass or less relative to the crosslinked rubber article.

[0013] Hereinafter, tetrafluoroethylene will also be referred to as "TFE," and the constituent units based on TFE will also be referred to as "TFE units." Furthermore, at least one compound selected from the group consisting of compounds (S1) to (S10) will be referred to as "compound (A)," and the total content of compound (A) in the crosslinked rubber article will also be referred to as "compound (A) content." Furthermore, the total content of compound (S1) in the crosslinked rubber article will also be referred to as "(S1) content." Furthermore, the total content of compound (S11) in the crosslinked rubber article will also be referred to as "(S11) content."

[0014] H(CF) ２ ) ｐ１ COOM １ (S1) H(CF ２ ) ｐ２ SO ３ M ２ (S2) F(CF) ２ ) ｐ３ COOM ３ (S3) F(CF)２ ) ｐ４ SO ３ M ４ (S4) X ５１ (CF ２ ) ｐ５ (OCF ２ CF ２ CF ２ ) ｑ５ OCF(X ５２ ) CF ２ COOM ５ (S5) X ６１ (CF ２ ) ｐ６ (OCF(X ６２ ) CF(X ６３ )) ｑ６ OCF(X ６４ ) COOM ６ (S6) X ７１ (CF ２ ) ｐ７ CF(X ７２ ) (OCF(X ７３ ) CF(X ７４ )) ｑ７ OCF(X ７５ ) COOM ７ (S7)

[0015]

[0016] X １０１ CF ２ (OCF ２ CF ２ ) ｑ１０ (OCF ２ ) ｒ１０ X １０２ (S10) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11)

[0017] In formulas (S1) to (S11), M １ ~M ９ Each is independently a hydrogen atom, Na, K, or NH ４ X ５１ , X ６１ , X ７１ , X ８１ , X ８２ , X９１ , and X ９２ Each of these is independently a hydrogen atom, a fluorine atom, or a chlorine atom, and X １０１ and X １０２ Each of these is independently a hydrogen atom, a fluorine atom, a COOH group, or a chlorine atom, and X １０１ and X １０２ At least one of them is COOH, X ５２ , X ６２ ~X ６４ , and X ７２ ~X ７５ Each of these is independently a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms, and Rf ８ ~Rf ９ Each of these is independently a fluorine-containing alkylene group having 1 to 20 carbon atoms, and X １１１ and X １１２ Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 and p3 are independently integers from 3 to 13, p2 and p4 are independently integers from 4 to 10, p5 to p7 are independently integers from 1 to 10, q5 to q7 are independently integers from 0 to 3, q8 to q9 are independently integers from 1 to 20, n8 to n9 are independently integers from 1 to 30, and q8 and n8 are the CF contained in compound (S8). ２ A combination of integers such that the number of elements is 30 or less, where q9 and n9 are the CFs of the compound (S9). ２ A combination of integers such that the number of groups is 30 or less, where q10, r10, q11, and r11 are each independent integers of 0 or greater, where q10 and r10 are a combination of integers such that the number average molecular weight of compound (S10) is between 300 and 2000, and q11 and r11 are a combination of integers such that the number average molecular weight of compound (S11) is between 300 and 2000. Here, Rf ８ ~Rf ９ The "fluorine-containing alkylene group" represented by is a group in which one or more hydrogen atoms in an alkylene group are replaced by fluorine atoms, and it may or may not contain hydrogen atoms, and is a group that does not contain any atoms other than carbon atoms, hydrogen atoms, and fluorine atoms. １１１ and X １１２Similarly, a "fluorine-containing alkyl group" represented by is a group in which one or more hydrogen atoms in the alkyl group are substituted with fluorine atoms, and may or may not have hydrogen atoms, and is a group that does not have any atoms other than carbon atoms, hydrogen atoms, and fluorine atoms.

[0018] The compounds (S1) to (S10) are generally used as emulsifiers containing fluorine atoms when producing fluorine-containing elastomers by emulsion polymerization of fluorine-containing monomers, or are compounds that may be produced as by-products during polymerization. When compound (A) is used as an emulsifier containing fluorine atoms to produce a fluorine-containing elastomer by emulsion polymerization, and the resulting fluorine-containing elastomer is crosslinked to produce a crosslinked rubber article, a large amount of compound (A) may remain in the crosslinked rubber article. Furthermore, even when a fluorine-containing elastomer is produced without using compound (A), compound (A) may be generated during the production process of the fluorine-containing elastomer. For example, when a fluorine-containing monomer containing TFE is emulsion polymerized using a hydrocarbon-based emulsifier to produce a fluorine-containing elastomer, compound (S1) may be generated as a by-product. The crosslinked rubber article produced in this way contains a large amount of compound (A) in addition to the crosslinked rubber, which is the crosslinked body of the fluorine-containing elastomer, so that compound (A) functions as a plasticizer when compressed. Therefore, cross-linked rubber articles may not recover easily after being released from compression, and the compression set of the cross-linked rubber articles may become large.

[0019] Furthermore, compound (S11) is generally used as a good solvent, dispersant, etc., during solution polymerization and suspension polymerization. Even when compound (S11) is used as a good solvent, dispersant, etc., to produce a fluorine-containing elastomer, and the resulting fluorine-containing elastomer is crosslinked to produce a crosslinked rubber article, compound (S11) may remain in the crosslinked rubber article. Also, even when compound (S11) is not used to produce a fluorine-containing elastomer, compound (S11) may be generated as a by-product during the production process of the fluorine-containing elastomer. And, similar to compound (A), compound (S11) may function as a plasticizer in the crosslinked rubber article, which may increase the compression set of the crosslinked rubber article.

[0020] In contrast, crosslinked rubber article A contains crosslinked rubber having TFE units, and the compound (A) content is 10,000 ppb by mass or less, the (S1) content is 1,000 ppb by mass or less, and the (S11) content is 1,000 ppb by mass or less. Crosslinked rubber article A is thought to have a small compression set due to the low content of compounds that function as plasticizers.

[0021] Methods for controlling the compound (A) content and (S1) content in the crosslinked rubber article A to be within the above range include, for example, not using compound (A) or using it in a small amount in the manufacturing process of the fluorine-containing elastomer that is the raw material for the crosslinked rubber having TFE units, not using or using in a small amount of additives such as hydrocarbon emulsifiers that generate compound (A) in the manufacturing process of the fluorine-containing elastomer, removing compound (A) before crosslinking the fluorine-containing elastomer, and methods combining these. Similarly, methods for controlling the (S11) content in the crosslinked rubber article A to be within the above range include, for example, not using or using in a small amount of compound (S11) in the manufacturing process of the fluorine-containing elastomer that is the raw material for the crosslinked rubber having TFE units, not using or using in a small amount of additives such as polymethyl methacrylate that generates compound (S11) in the manufacturing process of the fluorine-containing elastomer, removing compound (S11) before crosslinking the fluorine-containing elastomer, and methods combining these.

[0022] (Preferred ranges for compound (A) content, (S1) content, and (S11) content) The compound (A) content in the crosslinked rubber article A is 0 ppb by mass, or greater than 0 ppb by mass and 10,000 ppb by mass or less. From the viewpoint of reducing compression set in the crosslinked rubber article, the compound (A) content is preferably 5,000 ppb by mass or less, more preferably 4,000 ppb by mass or less, even more preferably 3,000 ppb by mass or less, particularly preferably 2,000 ppb by mass or less, extremely preferably 1,000 ppb by mass or less, and most preferably 500 ppb by mass or less. If the crosslinked rubber article A contains compound (A), the compound (A) content may be 10 to 5,000 ppb by mass, 25 to 4,000 ppb by mass, or 50 to 3,000 ppb by mass.

[0023] The (S1) content in the crosslinked rubber article A is either 0 ppb by mass or greater than 0 ppb by mass and less than or equal to 1000 ppb by mass. From the viewpoint of reducing compression set in the crosslinked rubber article, the (S1) content is preferably 500 ppb by mass or less, more preferably 250 ppb by mass or less, even more preferably less than 100 ppb by mass, particularly preferably 50 ppb by mass or less, and extremely preferably 25 ppb by mass or less. If the crosslinked rubber article A contains compound (S1), the (S1) content may be 10 to 500 ppb by mass, 25 to 250 ppb by mass, or 50 to 100 ppb by mass.

[0024] The (S11) content in crosslinked rubber article A is 0 ppb by mass, or greater than 0 ppb by mass and less than or equal to 1000 ppb by mass. From the viewpoint of reducing compression set in the crosslinked rubber article, the (S11) content is preferably 500 ppb by mass or less, more preferably 250 ppb by mass or less, even more preferably 100 ppb by mass or less, and particularly preferably 25 ppb by mass or less. If crosslinked rubber article A contains compound (S11), the (S11) content may be 25 to 100 ppb by mass, 50 to 250 ppb by mass, or 100 to 500 ppb by mass.

[0025] The content of compounds (A), (S1), and (S11) is determined by crushing the cross-linked rubber article to be measured, extracting the compounds to be measured into a solvent, and then analyzing them by liquid chromatography-mass spectrometry. The specific measurement method, measurement conditions, and calculation method are as described in the examples.

[0026] <Second Embodiment> The crosslinked rubber article according to the second embodiment of this disclosure (hereinafter also referred to as "crosslinked rubber article B") contains crosslinked rubber including a tetrafluoroethylene-based constituent unit (TFE unit), and one or more CF ２ It has a group and one or more ionic functional groups, and the ionic functional groups are COOM, SO ３ M, PO ４ M, or SO ４ M is a hydrogen atom, Na, K, or NH ４ Therefore, CF per ionic functional group ２ When compound (B) is defined as a compound having 30 or fewer groups, lacking carbon-carbon double bonds and carbon-carbon triple bonds, and having a number-average molecular weight of 3000 or less, the crosslinked rubber article may not contain compound (B), or may contain compound (B) with a total content of compound (B) of 10000 ppb by mass or less, and may not contain compound (S1) from compound (B), or may contain compound (S1) with a content of 1000 ppb by mass or less, and may not contain compound (S11), which is a compound other than compound (B), or may contain compound (S11) with a content of 1000 ppm by mass or less.

[0027] Hereinafter, the content of compound (B) in the crosslinked rubber article will also be referred to as the "compound (B) content."

[0028] Compound (B) is a compound commonly used as an emulsifier containing a fluorine atom when producing fluorine-containing elastomers by emulsion polymerization of fluorine-containing monomers. Similar to compound (A), when compound (B) is used as an emulsifier containing a fluorine atom to produce fluorine-containing elastomers, and the resulting fluorine-containing elastomers are crosslinked to produce crosslinked rubber articles, compound (B) may remain in the crosslinked rubber articles. Furthermore, even when fluorine-containing elastomers are produced without using an emulsifier containing a fluorine atom, compound (B) may be generated during the production process of the fluorine-containing elastomers. And, similar to compound (A), compound (B) may function as a plasticizer in the crosslinked rubber articles, potentially increasing the compression set of the crosslinked rubber articles.

[0029] In contrast, crosslinked rubber article B contains crosslinked rubber having TFE units, and the compound (B) content is 10,000 ppb by mass or less, the (S1) content is 1,000 ppb by mass or less, and the (S11) content is 1,000 ppb by mass or less. Crosslinked rubber article B is thought to have a small compression set due to the low content of compounds that function as plasticizers. The method for controlling the compound (B) content and (S1) content in crosslinked rubber article B to the above range is the same as the method for controlling the compound (A) content and (S1) content in crosslinked rubber article A described above. The method for controlling the (S11) content in crosslinked rubber article B to the above range is the same as the method for controlling the (S11) content in crosslinked rubber article A.

[0030] (Preferred ranges for compound (B) content, (S1) content, and (S11) content) The compound (B) content in the crosslinked rubber article B is 0 ppb by mass, or greater than 0 ppb by mass and 10,000 ppb by mass or less. From the viewpoint of reducing compression set in the crosslinked rubber article, the compound (B) content is preferably 5,000 ppb by mass or less, more preferably 4,000 ppb by mass or less, even more preferably 3,000 ppb by mass or less, particularly preferably 2,000 ppb by mass or less, extremely preferably 1,000 ppb by mass or less, and most preferably 500 ppb by mass or less. If the crosslinked rubber article B contains compound (B), the compound (B) content may be 10 to 5,000 ppb by mass, 25 to 4,000 ppb by mass, or 50 to 3,000 ppb by mass.

[0031] The (S1) content in the crosslinked rubber article B is either 0 ppb by mass or greater than 0 ppb by mass and less than or equal to 1000 ppb by mass. From the viewpoint of reducing compression set in the crosslinked rubber article, the (S1) content is preferably 500 ppb by mass or less, more preferably 250 ppb by mass or less, even more preferably less than 100 ppb by mass, particularly preferably 50 ppb by mass or less, and extremely preferably 25 ppb by mass or less. If the crosslinked rubber article B contains compound (S1), the (S1) content may be 10 to 500 ppb by mass, 25 to 250 ppb by mass, or 50 to 100 ppb by mass.

[0032] The (S11) content in the crosslinked rubber article B is either 0 ppb by mass or greater than 0 ppb by mass and less than or equal to 1000 ppb by mass. From the viewpoint of reducing compression set in the crosslinked rubber article, the (S11) content is preferably 500 ppb by mass or less, more preferably 250 ppb by mass or less, even more preferably 100 ppb by mass or less, and particularly preferably 25 ppb by mass or less. If the crosslinked rubber article B contains compound (S11), the (S11) content may be 25 to 100 ppb by mass, 50 to 250 ppb by mass, or 100 to 500 ppb by mass.

[0033] The content of compounds (B), (S1), and (S11) is determined by crushing the cross-linked rubber article to be measured, extracting the compounds to be measured into a solvent, and then analyzing them by liquid chromatography-mass spectrometry. The specific measurement method, measurement conditions, and calculation method are as described in the examples.

[0034] (Compound (B)) Compound (B) is, as described above, 1 or more CF ２ It has a group and one or more ionic functional groups, and the CF per ionic functional group ２ A compound having 30 or fewer groups, lacking carbon-carbon double bonds and carbon-carbon triple bonds, and having a number-average molecular weight of 3000 or less. Ionic functional groups include COOM and SO. ３ M, PO ４ M, or SO ４ M is a hydrogen atom, Na, K, or NH ４ Among these, the ionic functional groups are COOM or SO ３ M is preferred, and COOM is more preferred. The number of ionic functional groups in one molecule can be, for example, 1 to 2, and 1 is preferred. CF per ionic functional group ２ The number of groups is 30 or less, may be 25 or less, 20 or less, 13 or less, or 10 or less. Also, the CF per ionic functional group ２ The number of elements is 1 or more, may be 2 or more, may be 3 or more, or may be 4 or more.

[0035] Specific examples of compound (B) include, for example, compounds (S1) to (S10). Furthermore, as a specific example of compound (B), the ionic functional groups of compounds (S1) to (S10) are PO ４ M, or SO ４ The compounds changed to M, and the ionic functional groups of compounds (S5) to (S10) were changed to SO ３ Compounds modified to M are also examples. The number-average molecular weight of compound (B) may be 300 to 3000 or 300 to 1000.

[0036] The following describes matters common to both Crosslinked Rubber Article A and Crosslinked Rubber Article B. Furthermore, the term "these Crosslinked Rubber Articles" may be used as a general term for both Crosslinked Rubber Article A and Crosslinked Rubber Article B.

[0037] <Crosslinked Rubber> This crosslinked rubber article contains crosslinked rubber containing TFE units. The crosslinked rubber is a crosslinked body of a fluorine-containing elastomer containing TFE units. The crosslinked rubber only needs to have TFE units and a crosslinked structure. Examples of crosslinked rubber include those with a solubility of less than 2 g / L in 1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorohexane (fluorine-containing solvent) at 25°C.

[0038] (Constituent Units) Crosslinked rubber may contain constituent units based on other monomers in addition to TFE units. Examples of other monomers include hexafluoropropylene (hereinafter also referred to as "HFP"), vinylidene fluoride (hereinafter also referred to as "VdF"), propylene, fluorinated vinyl ether, fluorinated allyl ether, and the like.

[0039] Examples of fluorinated vinyl ethers include compounds represented by the following formula (1A): CF ２ =CF-O-R ｆ１ ...(1A) In formula (1A), R ｆ１ R represents a fluoroalkyl group having 1 to 10 carbon atoms. ｆ１ The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3, from the viewpoint of superior rubber properties. The fluoroalkyl group may be linear or branched. From the viewpoint of improving the heat resistance of the crosslinked rubber article, the fluoroalkyl group is preferably a perfluoroalkyl group. From the viewpoint of improving the heat resistance of the crosslinked rubber article, the fluorine-containing vinyl ether is preferably a perfluoro(alkyl vinyl ether) (hereinafter also referred to as "PAVE").

[0040] Specific examples of PAVE include perfluoro(methyl vinyl ether) (hereinafter also referred to as "PMVE"), perfluoro(ethyl vinyl ether) (hereinafter also referred to as "PEVE"), and perfluoro(propyl vinyl ether) (hereinafter also referred to as "PPVE"). Among these, PMVE or PPVE is preferred, with PMVE being more preferred, due to its superior rubber properties.

[0041] Examples of fluorine-containing allyl ethers include compounds represented by the following formula (2A): CF ２ = CF - CF ２ O-R ｆ２ ...(2A) In formula (2A), R ｆ２ R represents a fluoroalkyl group having 1 to 10 carbon atoms. ｆ２ The number of carbon atoms is preferably 1 to 8, more preferably 1 to 6, even more preferably 1 to 5, and particularly preferably 1 to 3, from the viewpoint of superior rubber properties. The fluoroalkyl group may be linear or branched. From the viewpoint of improving the heat resistance of the crosslinked rubber article, the fluoroalkyl group is preferably a perfluoroalkyl group. From the viewpoint of improving the heat resistance of the crosslinked rubber article, the fluorine-containing allyl ether is preferably a perfluoro(alkylallyl ether) (hereinafter also referred to as "PAAE").

[0042] Specific examples of PAAEs include perfluoro(methyl allyl ether) (hereinafter also referred to as "PMAE"), perfluoro(ethyl allyl ether) (hereinafter also referred to as "PEAE"), and perfluoro(propyl allyl ether) (hereinafter also referred to as "PPAE"). Among these, PMAE or PPAE are preferred, with PMAE being more preferred, due to their superior rubber properties.

[0043] Other monomers include, for example, ethylene, propylene, vinyl chloride, vinylidene chloride, chlorotrifluoroethylene, and fluoroalkylethylene.

[0044] From the viewpoint of obtaining rubber elasticity, the other monomers preferably include at least one selected from the group consisting of PAVE, propylene, VdF, and HFP, and more preferably PAVE. In other words, the crosslinked rubber preferably further includes, in addition to TFE units, at least one selected from the group consisting of PAVE-based units (hereinafter also called "PAVE units"), propylene-based units (hereinafter also called "P units"), VdF-based units (hereinafter also called "VdF units"), and HFP-based units (hereinafter also called "HFP units"), and more preferably PAVE units.

[0045] The crosslinked rubber may contain TFE units and PAVE units, TFE units and P units, or TFE units, VdF units, and HFP units. When the crosslinked rubber contains TFE units and PAVE units, the TFE unit content in the crosslinked rubber is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE units and PAVE units, from the viewpoint of superior rubber properties. The preferred ratio is the same when PAVE units are PMVE units (i.e., when the crosslinked rubber contains TFE units and PMVE units), and when PAVE units are PPVE units (i.e., when the crosslinked rubber contains TFE units and PPVE units). When the crosslinked rubber contains TFE units and P units, the TFE unit content in the crosslinked rubber is preferably 10 to 95 mol%, more preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE units and P units, from the standpoint of superior rubber properties. When the crosslinked rubber contains TFE units, VdF units and HFP units, the TFE unit content in the crosslinked rubber is preferably 3 to 60 mol%, more preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE units, VdF units, and HFP units, from the standpoint of superior rubber properties.

[0046] (Crosslinking Structure) Examples of crosslinking structures in crosslinked rubber include crosslinking structures derived from heterocyclic rings (hereinafter also referred to as "heterocyclic crosslinking structures"), crosslinking structures derived from hydrocarbon groups (hereinafter also referred to as "hydrocarbon crosslinking structures"), crosslinking structures via ether groups, and crosslinking structures via amino groups. Examples of heterocyclic crosslinking structures include oxazole ring structures and triazine ring structures. Examples of crosslinked rubber having heterocyclic crosslinking structures include crosslinked bodies of compositions containing a fluorine-containing elastomer having one or more cyano groups (hereinafter also referred to as "CN-based crosslinked bodies"). Examples of hydrocarbon crosslinking structures include crosslinking structures via alkyl groups. Examples of crosslinked rubber having hydrocarbon crosslinking structures include crosslinked bodies of compositions containing a fluorine-containing elastomer having at least one atom selected from the group consisting of bromine and iodine atoms and an organic peroxide (hereinafter also referred to as "PO-based crosslinked bodies"), and crosslinked bodies obtained by electron beam crosslinking of a fluorine-containing elastomer composition.

[0047] Examples of crosslinked rubber having a crosslinked structure via ether groups (hereinafter also referred to as "ether crosslinked structure") include crosslinked bodies of compositions containing a fluorine-containing elastomer containing VdF units and a polyol compound (hereinafter also referred to as "polyol-based crosslinked bodies"). Examples of crosslinked rubber having a crosslinked structure via amino groups (hereinafter also referred to as "amino crosslinked structure") include crosslinked bodies of compositions containing a fluorine-containing elastomer containing VdF units and a polyamine compound (hereinafter also referred to as "polyamine-based crosslinked bodies").

[0048] Crosslinked rubber is preferably made of at least one of a heterocyclic crosslinked structure and a hydrocarbon crosslinked structure, in order to have excellent rubber properties. Crosslinked rubber is preferably made of CN-based crosslinked material or PO-based crosslinked material.

[0049] The constituent units and types and ratios of the cross-linked rubber are confirmed as follows. Specifically, the cross-linked rubber article to be measured is confirmed by Fourier transform infrared spectroscopy analysis using the total internal reflection (ATR) method.

[0050] <Total Content of Metal Elements> From the viewpoint of suppressing contamination of the surrounding area during use, it is preferable that this crosslinked rubber article does not contain metal elements, or contains metal elements, with the total content of metal elements being greater than 0 ppm by mass and 50 ppm by mass or less relative to the crosslinked rubber article. In particular, when this crosslinked rubber article is used as a sealing material for semiconductor manufacturing equipment, the release of metal components that affect semiconductor products is suppressed by keeping the total content of metal elements below the above upper limit. Hereinafter, the total content of metal elements relative to the entire crosslinked rubber article will also be referred to as "metal content". From the viewpoint of suppressing contamination of the surrounding area during use, the metal content is preferably 50 ppm by mass or less, more preferably 20 ppm by mass or less, even more preferably 10 ppm by mass or less, and particularly preferably 5 ppm by mass or less. If this crosslinked rubber article contains metal elements, the metal content may be 0.3 ppm by mass or more.

[0051] The metal content is determined by placing the cross-linked rubber material to be measured in a platinum crucible, ashing it in a high-temperature electric heating furnace, treating it with sulfuric acid fumes, and then measuring the resulting solution using an inductively coupled plasma mass spectrometer. Specifically, the content of 29 metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, Bi) is measured using the absolute calibration curve method, and the total value is defined as the above-mentioned metal content.

[0052] Methods for controlling the metal content in the crosslinked rubber article to the aforementioned range include, for example, not using or using components containing metal elements in small amounts during the manufacturing process of the crosslinked rubber article. Specifically, for example, in the process of agglomerating particles of fluorine-containing elastomer, which is the raw material for crosslinked rubber, one method is to use a flocculant that does not contain metal elements (e.g., nitric acid) instead of a flocculant that contains metal elements (e.g., potassium aluminum sulfate) as the flocculant.

[0053] <Other Components> Crosslinked rubber article A may contain other components besides crosslinked rubber, provided that the compound (A) content, (S1) content, and (S11) content are within the above range. Crosslinked rubber article B may contain other components besides crosslinked rubber, provided that the compound (B) content, (S1) content, and (S11) content are within the above range. This crosslinked rubber article may also contain other components such as monomers and additives used in the production of fluorine-containing elastomers, by-products generated by the production of fluorine-containing elastomers, and additives such as crosslinking agents used for crosslinking fluorine-containing elastomers.

[0054] This crosslinked rubber article may contain additives such as pigments, fillers, reinforcing agents, processing aids, and metal oxides as other components. Examples of fillers or reinforcing agents include carbon black, titanium dioxide, silicon dioxide, clay, talc, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, TFE / ethylene copolymer, TFE / propylene copolymer, TFE / vinylidene fluoride copolymer, and TFE / PAVE copolymer. Examples of processing aids include those that are well known. Examples of processing aids that exhibit lubricant function include fatty acid metal salts (sodium stearate, calcium stearate, etc.), synthetic waxes (polyethylene wax, etc.), and fatty acid esters (glycerin monooleate, etc.). Examples of metal oxides include divalent metal oxides such as magnesium oxide, calcium oxide, zinc oxide, and lead oxide.

[0055] <Method for Manufacturing Crosslinked Rubber Articles> The crosslinked rubber article is manufactured through a crosslinking process in which a solid composition containing a fluorine-containing elastomer containing TFE units and additives such as crosslinking agents and fillers used as needed is molded and crosslinked as needed. Here, the solid composition is solid at 25°C. As a method for obtaining a crosslinked rubber article A in which the compound (A) content, (S1) content, and (S11) content are within the above ranges, one method is to use a solid composition in which compound (A) is not present or present in a small amount, and compound (S11) is not present or present in a small amount. Examples of solid compositions used in the above method include a solid composition containing a fluorine-containing elastomer having TFE units and at least one selected from the group consisting of bromine atoms, iodine atoms, and cyano groups, wherein the total content of compound (A) in the solid composition is 10,000 ppb by mass or less, the total content of compound (S1) in the solid composition is 1,000 ppb by mass or less, and the total content of compound (S11) in the solid composition is 1,000 ppb by mass or less.

[0056] Furthermore, as a method for obtaining a crosslinked rubber article B in which the compound (B) content, (S1) content, and (S11) content are within the aforementioned ranges, one method is to use a solid composition in which compound (B) is not present or present in small amounts, and compound (S11) is not present or present in small amounts. An example of a solid composition used in the above method is a solid composition containing a fluorine-containing elastomer having TFE units and at least one selected from the group consisting of bromine atoms, iodine atoms, and cyano groups, wherein the total content of compound (B) in the solid composition is 10,000 ppb by mass or less, the total content of compound (S1) in the solid composition is 1,000 ppb by mass or less, and the total content of compound (S11) in the solid composition is 1,000 ppb by mass or less.

[0057] The above solid composition may also contain additives such as pigments, fillers, reinforcing agents, processing aids, and metal oxides as other components.

[0058] The above solid composition may be obtained, for example, through a polymerization step to produce a fluorine-containing elastomer containing TFE units by polymerizing a monomer containing TFE, and may also be obtained through a mixing step in which the fluorine-containing elastomer is mixed with additives such as a crosslinking agent and a filler, if necessary. If the polymerization step is a step to produce an aqueous dispersion in which particles of fluorine-containing elastomer are dispersed in an aqueous medium, it may further include an agglomeration and separation step in which the particles of fluorine-containing elastomer are agglomerated in the aqueous dispersion and separated from the aqueous medium.

[0059] As a method for obtaining a solid composition with low content of compound (A) or compound (B) and compound (S11), for example, a method using manufacturing method A or manufacturing method B described later in the polymerization step can be mentioned. In manufacturing methods A and B, a fluorine-containing elastomer is produced under conditions in which emulsifiers containing fluorine atoms and compound (S11) are substantially absent, so the content of compound (A) or compound (B) and compound (S11) in the solid composition is reduced. Therefore, a crosslinked rubber article in which the content of compound (A) or compound (B), (S1) and (S11) are within the aforementioned ranges is easily obtained.

[0060] Furthermore, as will be described later, in manufacturing methods A and B, fluorine-containing elastomers may also be produced under conditions where emulsifiers without fluorine atoms are substantially absent. For example, when a fluorine-containing elastomer is produced in the presence of a hydrocarbon emulsifier, which is a type of emulsifier that does not contain fluorine atoms, compound (S1) may be generated during the manufacturing process. In contrast, by producing a fluorine-containing elastomer under conditions where not only emulsifiers containing fluorine atoms but also emulsifiers without fluorine atoms are substantially absent, the content of compound (S1) in the solid composition can be further reduced.

[0061] Furthermore, as will be described later, manufacturing methods A and B produce an aqueous dispersion in which particles of fluorine-containing elastomer are dispersed in an aqueous medium. Therefore, the content of compound (A) or compound (B) and compound (S11) in the solid composition may be reduced by removing compound (A) or compound (B) and compound (S11) in the coagulation and separation step performed after the polymerization step.

[0062] The following describes manufacturing methods A and B, which are examples of polymerization processes, as well as the aggregation and separation process, the mixing process, and the crosslinking process.

[0063] (Manufacturing Method A) Manufacturing Method A includes a step of polymerizing monomer A containing TFE in the presence of compound (X) represented by the following formula (X) and an aqueous medium, and under conditions where an emulsifier and compound (S11) having a fluorine atom are substantially absent. CX １ X ２ = CX ３ -L-Z...(X) In formula (X), １ and X ２ Each of these is independently a hydrogen atom, a chlorine atom, or an alkyl group, and X ３ L is a hydrogen atom or an alkyl group, L is a single bond or a divalent linking group, and Z is an anionic group or a salt of an anionic group.

[0064] -Emulsifiers, etc.- Manufacturing method A is carried out under conditions where emulsifiers containing fluorine atoms are substantially absent. Substantially absent emulsifiers containing fluorine atoms means that, in the production of the fluorine-containing elastomer, the content of emulsifiers containing fluorine atoms is 10 ppm by mass or less, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less, based on the total amount of the aqueous medium. The lower limit of the content of emulsifiers containing fluorine atoms is 0 ppb by mass.

[0065] Method A is preferably carried out under conditions in which emulsifiers containing fluorine atoms and emulsifiers not containing fluorine atoms are substantially absent, in that the (S1) content of the crosslinked rubber article produced is within the aforementioned range. The substantially absence of emulsifiers containing fluorine atoms and emulsifiers not containing fluorine atoms (hereinafter collectively referred to as "emulsifiers") means that, in the production of fluorine-containing elastomers, the emulsifier content is 10 ppm by mass or less, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less, relative to the total amount of the aqueous medium. The lower limit of the emulsifier content is 0 ppb by mass. The content of various emulsifiers can be measured using a liquid chromatograph-mass spectrometer.

[0066] Examples of emulsifiers include water-soluble emulsifiers. A water-soluble emulsifier means an emulsifier whose solubility in 1000 g of water at 25°C is 100 mg or more, while a non-water-soluble emulsifier means an emulsifier other than the water-soluble emulsifiers mentioned above. Water-soluble emulsifiers may be either ionic or nonionic. Examples of emulsifiers include those that do not have a carbon-carbon double bond. Note that compound (X) mentioned above does not qualify as an emulsifier. Furthermore, in manufacturing method A and manufacturing method B described later, the monomers used in polymerization and the fluorine-containing elastomers obtained by polymerization do not qualify as emulsifiers.

[0067] A fluorine-free emulsifier is an emulsifier that does not contain fluorine atoms and has hydrocarbon groups such as alkyl groups as its hydrophobic portion. It is also possible to substitute the hydrogen atoms of the hydrocarbon groups of a fluorine-free emulsifier with halogen atoms other than fluorine atoms. Examples of fluorine-free emulsifiers include ionic hydrocarbon emulsifiers and nonionic hydrocarbon emulsifiers.

[0068] Examples of ionic hydrocarbon emulsifiers include anionic hydrocarbon emulsifiers. Anionic hydrocarbon emulsifiers refer to emulsifiers having a negatively charged hydrophilic portion such as a carboxylic acid group, sulfonic acid group, sulfate group, phosphonic acid group, and phosphate group, and a hydrocarbon group such as an alkyl group as a hydrophobic portion. Specific examples of anionic hydrocarbon emulsifiers include sodium dodecyl sulfate, a highly branched C10 tertiary carboxylic acid supplied by Resolution Performance Products as Versatic® 10, sodium linear alkyl polyethersulfonate supplied by BASF as the Avanel® S series, and the sulfosuccinate emulsifier Lankropol® K8300 available from AkzoNobelSurfaceChemistryLLC.

[0069] Nonionic hydrocarbon emulsifiers are emulsifiers that exhibit surface activity without dissociating into ions in water and have hydrocarbon groups such as alkyl groups as hydrophobic portions. Examples of hydrophilic portions of nonionic hydrocarbon emulsifiers include water-soluble functional groups such as polyethylene oxide chains obtained from the polymerization of ethylene oxide. Examples of nonionic hydrocarbon emulsifiers include polyalkylene oxide block copolymers, such as block copolymers having polyethylene oxide and polypropylene oxide.

[0070] Another example of a nonionic hydrocarbon emulsifier is the emulsifier described in paragraphs

[0043] to

[0052] of Japanese Patent Publication No. 2016-537499.

[0071] Emulsifiers containing fluorine atoms and emulsifiers not containing fluorine atoms may also contain silicon atoms. Examples of emulsifiers containing silicon atoms include siloxane emulsifiers. Siloxane emulsifiers are hydrocarbon-containing emulsifiers having a siloxane skeleton. Examples of siloxane emulsifiers include those described in U.S. Patent No. 6,841,616 (Wille et al.) and U.S. Patent No. 7,977,438 (Brothers et al.).

[0072] Emulsifiers containing fluorine atoms and emulsifiers not containing fluorine atoms may be polymer emulsifiers. Examples of polymer emulsifiers include polymers having hydrophilic groups in their side chains. Such polymer emulsifiers include polymers containing units based on compounds having both a polymerizable site and a hydrophilic group. Also included are polymers obtained by post-treatment such as hydrolysis of polymers containing units based on compounds that have a group that can become a hydrophilic group, even if they do not initially have a hydrophilic group. Specific examples of polymer emulsifiers include polymethyl methacrylate, which is an emulsifier not containing fluorine atoms.

[0073] When polymerizing monomer A under conditions where an emulsifier without fluorine atoms is present, typically 0.1 to 15 parts by mass of the emulsifier without fluorine atoms are used per 100 parts by mass of the aqueous medium.

[0074] Manufacturing method A is carried out under conditions in which compound (S11) is substantially absent. "Substantially absent" means that, in the production of the fluorine-containing elastomer, the content of compound (S11) is 10 ppm by mass or less, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less, relative to the total amount of the aqueous medium. The lower limit of the compound (S11) content is 0 ppb by mass.

[0075] -Aqueous Media- Manufacturing method A is carried out under conditions in which an aqueous medium is present. Specific examples of aqueous media include water and mixed solvents of water and water-soluble organic solvents. Specific examples of water-soluble organic solvents include tert-butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol.

[0076] - Compound (X) - Manufacturing method A is carried out under conditions in which compound (X) is present. In formula (X), X １ and X ２ The alkyl group represented by may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group is preferably 1 to 10, more preferably 1 to 3, and even more preferably 1. １ and X ２From the viewpoint of increasing the number of particles in the resulting fluorine-containing elastomer, hydrogen atoms are preferred in all cases. In formula (X), X ３ Specific examples and preferred embodiments of the alkyl group represented by X １ and X ２ The specific examples and preferred embodiments of alkyl groups are the same as in X. ３ From the viewpoint of increasing the number of particles in the resulting fluorine-containing elastomer, hydrogen atoms are preferred.

[0077] In formula (X), the divalent linking group represented by L is an alkylene group, a carbonyl group, an ether bond, a thioether bond, a sulfonyl group, -NH-, or -SiH. ２ -, phenylene group, -CF ２ - and groups formed by combining two or more of these are examples. Examples of groups formed by combining two or more of these include ester bonds, thioester bonds, amide bonds, sulfonamide bonds, combinations of alkylene groups and ether bonds, combinations of alkylene groups and ester bonds, and combinations of alkylene groups and amide bonds. The alkylene group may be linear, branched, or cyclic, with linear or branched being preferred, and branched being more preferred. Examples of the number of carbon atoms in the alkylene group include 1 to 6, and 1 to 4 being preferred.

[0078] Specific examples of L include single bonds, alkylene groups, ether bonds, ester bonds, * Ｃ -CO-NH-R-* Ｚ Examples include single bonds, alkylene groups having 1 to 6 carbon atoms, and * Ｃ -CO-NH-R-* Ｚ Preferably, a single bond, an alkylene group having 1 to 2 carbon atoms, and * Ｃ -CO-NH-R-* Ｚ This is preferable. Here, * Ｃ * is the bonding site with the carbon atom in formula (X), Ｚ is the bonding site with Z in formula (X), and R is an alkylene group having 1 to 6 carbon atoms.

[0079] In formula (X), the anionic group represented by Z is, for example, -SO ３ H, -OSO ３H, -P(=O)(OH) ２ , -OP(=O)(OH) ２ Alternatively, -COOH can be used. Examples of salts of anionic groups include groups in which the hydrogen ion of the above anionic group is replaced with a cation other than a hydrogen ion. Examples of cations include metal ions, ammonium ions, imidazolium cations, pyrrolidinium cations, pyridinium cations, piperidinium cations, and phosphonium cations. Examples of metal ions include alkali metal ions such as sodium ions, potassium ions, and lithium ions; and alkaline earth metal ions such as calcium ions and magnesium ions. Z is -SO ３ M, -OSO ３ M, -P (=O) (OM) ２ , -OP(=O)(OM) ２ Alternatively, -COOM is preferable. As for Z, from the viewpoint of productivity, -SO ３ M and -COOM are preferred, and -SO ３ Na and -COONa are more preferred, and -SO ３ Na is even more preferable.

[0080] M is a hydrogen atom, a metal atom, N (R Ｍ１ ) ４ or P(R) Ｍ２ ) ４ And R Ｍ１ and R Ｍ２ Each of these is independently a hydrogen atom or a substituent. The metal atom represented by M is preferably a metal atom of Group 1, and more preferably Li, Na, or K. Ｍ１ and R Ｍ２ The substituent represented by is preferably a monovalent organic group, more preferably a monovalent hydrocarbon group, and even more preferably an alkyl group or an aromatic hydrocarbon group. The substituent has 1 to 10 carbon atoms. The alkyl group may be linear, branched, or cyclic. The aromatic hydrocarbon group may be monocyclic or polycyclic. A phenyl group is preferred as the aromatic hydrocarbon group.

[0081] Examples of the molecular weight of compound (X) include 70 to 500, and from the viewpoint of dispersion stability, 70 to 450 is preferred, and 100 to 300 is more preferred.

[0082] Specific examples of compound (X) include vinyl sulfonic acid, vinyl phosphonic acid, (meth)acrylic acid, allyl sulfonic acid, allyl phosphonic acid, butenic acid, crotonic acid, vinyl acetate, 2-sulfoethyl methacrylic acid, 4-vinylbenzenesulfonic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, N-tigroylglycine, 6-acrylamidohexanoic acid, 1,1-difluoro-2-methyl-2-[(1-oxo-2-propen-1-yl)amino]-1-propanesulfonic acid, 3-methyl-3-[(2-methyl-1-oxo-2-propen-1-yl)amino]-2-butanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid, 2,3-dimethyl-3-[(1-oxo-2-propen-1-yl)amino]-2-butanesulfonic acid, and their salts. Examples of the above-mentioned metal salts include salts of metal atoms represented by M.

[0083] The compound (X) is preferably a vinyl compound having a sulfonic acid group, a phosphonic acid group, or a carboxyl group, an allyl compound having a sulfonic acid group, a phosphonic acid group, or a carboxyl group, (meth)acrylic acid, (meth)acrylamide having a sulfonic acid group, a phosphonic acid group, or a carboxyl group, and metal salts thereof. Vinyl sulfonic acid, sodium vinyl sulfonate, allyl sulfonic acid, sodium allyl sulfonate, 2-acrylamide-2-methyl-1-propanesulfonic acid, sodium 2-acrylamide-2-methyl-1-propanesulfonate, 2-methacrylamide-2-methyl-1-propanesulfonic acid, or sodium 2-methacrylamide-2-methyl-1-propanesulfonate. Note that the above "(meth)acrylic acid" is a concept that includes both acrylic acid and methacrylic acid, and the above "(meth)acrylamide" is a concept that includes both acrylamide and methacrylamide.

[0084] The content of compound (X) is preferably 0.1 to 5000 ppm by mass, more preferably 0.2 to 1000 ppm by mass, even more preferably 0.3 to 500 ppm by mass, and particularly preferably 0.5 to 100 ppm by mass, relative to the total amount of the aqueous medium.

[0085] -Monomer A- In manufacturing method A, monomer A containing TFE is polymerized. Monomer A further contains other monomers if the crosslinked rubber contained in the crosslinked rubber article contains constituent units based on the other monomers mentioned above. In addition to TFE, monomer A preferably further contains at least one selected from the group consisting of PAVE, propylene, VdF, and HFP units, and more preferably further contains PAVE. Monomer A may contain TFE and PAVE, may contain TFE and propylene, or may contain TFE, VdF, and HFP. When monomer A contains TFE and PAVE, the TFE content in monomer A is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE and PAVE, in order to obtain a polymer with superior rubber properties. The preferred proportions are the same when PMVE is used as PAVE (i.e., when monomer A contains TFE and PMVE) and when PPVE is used as PAVE (i.e., when monomer A contains TFE and PPVE). When monomer A contains TFE and propylene, the TFE content in monomer A is 10 to 95 mol%, preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE and propylene, in order to obtain a polymer with superior rubber properties. When monomer A contains TFE, VdF and HFP, the TFE content in monomer A is 3 to 60 mol%, preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE, VdF, and HFP, in order to obtain a polymer with superior rubber properties.

[0086] Furthermore, monomer A may further contain a crosslinking monomer for forming the crosslinked structure of the crosslinked rubber. For example, if the crosslinked rubber has a heterocyclic crosslinked structure, monomer A may contain a monomer having a cyano group as the crosslinking monomer. Also, for example, if the crosslinked rubber has a hydrocarbon crosslinked structure, monomer A may contain a monomer having at least one selected from the group consisting of bromine atoms and iodine atoms as the crosslinking monomer. Furthermore, monomer A may contain a monomer having two or more polymerizable unsaturated bonds (hereinafter also referred to as "BO") as the crosslinking monomer.

[0087] The monomer having a cyano group is not particularly limited as long as it is a compound having a cyano group and a polymerizable group, for example, a compound represented by the following formula (Y). CR １１ R １２ =CR １３ -R １４ -CN...(Y) In formula (Y), R １１ , R １２ , and R １３ Each of these independently represents a hydrogen atom, a fluorine atom, or a methyl group. １４ This refers to a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms.

[0088] Due to its excellent polymerization reactivity, R １１ , R １２ , and R １３ It is preferable that R is a fluorine atom or a hydrogen atom. １１ , R １２ , and R １３ It is more preferable that all of them are fluorine atoms or all of them are hydrogen atoms, as this provides superior release properties and heat resistance for the crosslinked rubber article. １１ , R １２ , and R １３ It is particularly preferable that all of them are fluorine atoms. １４ The chain may be linear, branched, or cyclic, with linear or branched being preferred. １４The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and particularly preferably 3 to 5. １４ It may or may not have etheric oxygen atoms, but it is preferable to have etheric oxygen atoms because it provides superior rubber properties. １４ The number of etheric oxygen atoms in is preferably 1 to 3, and particularly preferably 1 or 2.

[0089] A specific example of a compound represented by formula (Y) is CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ CN (hereinafter also referred to as "8CNVE"), CF ２ = CFO (CF ２ ) ５ CN (hereinafter also referred to as "MV5CN"), CF ２ = CFOCF ２ CF ２ CF ２ OCF (CF ３ ) CN and CF ２ = CFO (CF ２ ) ３ CN is one example, and 8CNVE or MV5CN is preferred because they offer superior release properties and heat resistance for crosslinked rubber articles.

[0090] From the viewpoint of obtaining superior mold release properties and physical properties of crosslinked rubber articles, the content of monomers having cyano groups is preferably 0.5 to 20 mol%, more preferably 0.5 to 15 mol%, even more preferably 0.5 to 10 mol%, and particularly preferably 0.5 to 5 mol%, relative to the total amount of monomer A.

[0091] Monomers having at least one atom selected from the group consisting of bromine and iodine atoms include monomers having a bromine atom and monomers having an iodine atom. A specific example of a monomer having a bromine atom is CF ２ = CFOCF ２ CF ２ CF ２ OCF ２ CF ２Examples include Br, bromotrifluoroethylene, 4-bromo-3,3,4,4-tetrafluorobutene-1 (BTFB), vinyl bromide, 1-bromo-2,2-difluoroethylene, perfluoroallyl bromide, 4-bromo-1,1,2-trifluorobutene-1, 4-bromo-1,1,3,3,4,4-hexafluorobutene, 4-bromo-3-chloro-1,1,3,4,4-pentafluorobutene, 6-bromo-5,5,6,6-tetrafluorohexene, 4-bromoperfluorobutene-1,3,3-difluoroallyl bromide. Also, 2-bromo-perfluoroethyl perfluorovinyl ether, CF ２ Br-R ｆ -O -CF = CF ２ (R ｆ Fluorinated compounds such as perfluoroalkylene groups, for example, CF ２ BrCF ２ O - CF = CF ２ , ROCF=CFBr, ROCBr=CF ２ Fluorovinyl ethers such as CH (where R is a lower alkyl group or fluoroalkyl group), specifically CH ３ OCF = CFBr or CF ３ CH ２ OCF = CFBr is one example.

[0092] A specific example of a monomer containing an iodine atom is given by the formula: CHR = CH-Z-CH ２ CHR-I (wherein multiple Rs are independently -H or -CH) ３ Z is a linear or branched C, which may contain one or more ether oxygen atoms. １ ~C １８ Examples include iodized olefins of a (per)fluoroalkylene group, or a (per)fluoropolyoxyalkylene group as disclosed in U.S. Patent No. 5,674,959. Also, as disclosed in U.S. Patent No. 5,717,036, formula: I(CH ２ CF ２ CF ２ ) ｎ OCF = CF ２ and ICH ２ CF ２ O[CF(CF３ ) CF ２ O] ｎ CF = CF ２ Examples of unsaturated ethers include those specified in the formula (where n = 1 to 3). Also, as disclosed in U.S. Specification 4,694,045, examples include iodoethylene, 4-iodo-3,3,4,4-tetrafluorobutene-1 (ITFB), 3-chloro-4-iodo-3,4,4-trifluorobutene, 2-iodo-1,1,2,2-tetrafluoro-1-(vinyloxy)ethane, 2-iodo-1-(perfluorovinyloxy)-1,1,-2,2-tetrafluoroethylene, 1,1,2,3,3,3-hexafluoro-2-iodo-1-(perfluorovinyloxy)propane, 2-iodoethyl vinyl ether, 3,3,4,5,5,5-hexafluoro-4-iodopentene, and iodotrifluoroethylene. Additionally, examples include allyl iodide and 2-iodo-perfluoroethyl perfluorovinyl ether.

[0093] Specific examples of polymerizable unsaturated bonds in BO include carbon-carbon double bonds (C=C) and carbon-carbon triple bonds (C≡C). Carbon-carbon double bonds (C=C) are more preferred as polymerizable unsaturated bonds. The number of polymerizable unsaturated bonds in BO is preferably 2 to 6, more preferably 2 or 3, and even more preferably 2, from the viewpoint of superior polymerization reactivity. Furthermore, BO is preferably equipped with fluorine atoms from the viewpoint of reducing the compression set of the crosslinked rubber article at high temperatures.

[0094] BO is preferably a monomer represented by formula (B1) because it provides superior release properties for crosslinked rubber articles. (CR ２１ R ２２ =CR ２３ -) ａ１ R ２４ (B1) In formula (B1), R ２１ , R ２２ and R ２３ Each of these is independently a hydrogen atom, a fluorine atom, a methyl group, or a trifluoromethyl group, and a1 is an integer from 2 to 6, R ２４This is a 1-valent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group, and a plurality of R ２１ , multiple R ２２ and multiple R ２３ Each of them may be the same or different from each other, but it is preferable that they be the same. a1 is preferably 2 or 3, and more preferably 2. From the viewpoint of superior polymerization reactivity of BO, R ２１ , R ２２ and R ２３ It is preferable that R is a fluorine atom or a hydrogen atom. ２１ , R ２２ and R ２３ It is more preferable that all of them are fluorine atoms or all of them are hydrogen atoms, as this provides better release properties for the crosslinked rubber article. ２１ , R ２２ and R ２３ It is even more preferable that all of them are fluorine atoms. ２４ The chain may be linear, branched, or annular, with linear or branched being preferred, and linear being more preferred. ２４ The number of carbon atoms is preferably 2 to 8, more preferably 3 to 7, even more preferably 3 to 6, and particularly preferably 3 to 5. ２４ It may or may not have etheric oxygen atoms, but it is preferable to have etheric oxygen atoms because it provides superior crosslinking reactivity and rubber properties. ２４ The number of etheric oxygen atoms in is preferably 1 to 6, more preferably 1 to 3, and even more preferably 1 or 2. ２４ The etheric oxygen atom in R ２４ It is preferable that it be located at the terminal end.

[0095] Among the monomers represented by formula (B1), suitable specific examples include the monomers represented by formula (B2) and the monomers represented by formula (B3). (CF ２ =CF-) ２ R ３１ (B2) In formula (B2), R ３１(CH) is a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group. ２ =CH-) ２ R ４１ (B3) In equation (B3), R ４１ This refers to a divalent perfluorohydrocarbon group having 1 to 10 carbon atoms, or a group having an etheric oxygen atom at the terminal or between carbon-carbon bonds of the perfluorohydrocarbon group.

[0096] A concrete example of a monomer represented by formula (B2) is CF ２ = CFO (CF ２ ) ２ OCF = CF ２ CF ２ = CFO (CF ２ ) ３ OCF = CF ２ CF ２ = CFO (CF ２ ) ４ OCF = CF ２ CF ２ = CFO (CF ２ ) ６ OCF = CF ２、 CF ２ = CFO (CF ２ ) ８ OCF = CF ２ CF ２ = CFO (CF ２ ) ２ OCF (CF ３ ) CF ２ OCF = CF ２ CF ２ = CFO (CF ２ ) ２ O(CF(CF ３ ) CF ２ O) ２ CF = CF ２ CF ２ = CFOCF ２ O(CF) ２ CF ２ O) ２ CF = CF ２ CF ２ = CFO (CF ２ O) ３ O(CF(CF３ ) CF ２ O) ２ CF = CF ２ CF ２ = CFOCF ２ CF (CF ３ ) O (CF ２ ) ２ OCF (CF ３ ) CF ２ OCF = CF ２ , and CF ２ = CFOCF ２ CF ２ O(CF) ２ O) ２ CF ２ CF ２ OCF = CF ２ Examples include: Among the monomers represented by formula (B2), a more suitable specific example of a monomer is CF ２ = CFO (CF ２ ) ３ OCF = CF ２ (Hereafter also referred to as "C3DVE"), and CF ２ = CFO (CF ２ ) ４ OCF = CF ２ (Hereafter, this will also be referred to as "C4DVE") is one example.

[0097] A concrete example of a monomer represented by formula (B3) is CH ２ =CH(CF ２ ) ２ CH=CH ２ ,CH ２ =CH(CF ２ ) ４ CH=CH ２ , and CH ２ =CH(CF ２ ) ６ CH=CH ２ Examples include CH ２ =CH(CF ２ ) ６ CH=CH ２ (Hereafter, this will also be referred to as "C6DV") is one example.

[0098] In particular, BO is preferably C3DVE or C4DVE.

[0099] - Chain transfer agent - In manufacturing method A, a chain transfer agent may be used. In particular, when the crosslinked rubber is a PO-based crosslinked body having a hydrocarbon crosslinked structure, a compound having at least one selected from the group consisting of bromine atoms and iodine atoms may be used as the chain transfer agent. This introduces at least one selected from the group consisting of bromine atoms and iodine atoms to the terminals of the fluorine-containing elastomer.

[0100] Examples of the above-mentioned chain transfer agent include the compound represented by formula (I). (Rf Ｉ ) - (X Ｉ ) ２ (I) In formula (I), Rf Ｉ X is a fluoroalkylene group having 1 to 16 carbon atoms, or an aromatic ring group. Ｉ Rf is an iodine atom or a bromine atom, and at least one of them is an iodine atom. Ｉ The fluoroalkylene group may be linear or branched. Ｉ A perfluoroalkylene group is preferred. Ｉ Ideally, all of them should be iodine atoms.

[0101] Compounds represented by formula (I) include 1,2-diiodoperfluoroethane, 1,3-diiodoperfluoropropane, 1,4-diiodoperfluorobutane (hereinafter also referred to as "perfluoro1,4-diiodobutane" or "C4DI"), 1,5-diiodoperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluoroctan, 1,3-diiodo-2-chloroperfluoropropane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,12-diiodoperfluorododecane, 1,16-diiodoperfluorohexadecane, and diiodome Examples include tan, 1,2-diiodoethane, 1,3-diiodo-n-propane, (2-iodoethyl) substituted derivatives of benzene, 1-iodo-4-bromoperfluorobutane, 1-iodo-6-bromoperfluorohexane, 1-iodo-8-bromoperfluoroctan, 1-bromo-2-iodoperfluoroethane, 1-bromo-3-iodoperfluoropropane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodomonobromo substituted derivatives of benzene, and diiodomonobromo substituted derivatives. C4DI is preferred as the compound represented by formula (I).

[0102] When the fluorine-containing elastomer contains iodine atoms, the proportion of iodine atoms is preferably 0.01 to 5.00% by mass, more preferably 0.01 to 2.00% by mass, and even more preferably 0.01 to 1.00% by mass, relative to the total mass of the fluorine-containing elastomer.

[0103] -Polymerization Initiator- A polymerization initiator may be used in manufacturing method A. The polymerization initiator used in manufacturing method A is preferably a water-soluble polymerization initiator, more preferably persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, more preferably organic polymerization initiators such as disuccinic acid peroxide and azobisisobutylamidine dihydrochloride, even more preferably persulfates, and particularly preferably ammonium persulfate. The amount of polymerization initiator used is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and even more preferably 0.01 to 2 parts by mass, per 100 parts by mass of monomer A. When a polymerization initiator is used, it may be added to the reactor all at once or in portions. When added in portions, it may be added in multiple stages or continuously.

[0104] -Polymerization conditions- The polymerization temperature is preferably 10 to 95°C, and more preferably 15 to 90°C. The polymerization pressure is preferably 0.5 to 4.0 MPaG, and more preferably 0.6 to 3.5 MPaG. The polymerization time is preferably 90 to 1000 minutes, and more preferably 90 to 800 minutes.

[0105] -Fluorine-containing elastomer- In manufacturing method A, for example, by carrying out a step of polymerizing monomer A, an aqueous dispersion A containing particles of fluorine-containing elastomer is obtained.

[0106] The average particle diameter of the fluorine-containing elastomer particles is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, and particularly preferably 150 nm or less, from the viewpoint of particle dispersion stability. The lower limit is preferably 2 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. As the average particle diameter of the fluorine-containing elastomer particles, the particle diameter calculated by analyzing the autocorrelation function obtained by dynamic light scattering using the monodisperse cumulant method, or D50 (median diameter), can be used. The above D50 is the particle diameter at the point on the cumulative curve where the cumulative volume is 50%, obtained by measuring the particle size distribution by laser diffraction and scattering, setting the total volume of the particle collection to 100%. As a specific method for measuring the average particle diameter, the method of the examples described later can be used.

[0107] The number of fluorine-containing elastomer particles in aqueous dispersion A is 2.0 × 10⁻⁶. １３ Preferably, 1.0 × 10¹ / mL or more. １４ More than 2.0 × 10¹ / mL is also preferable. １４ A concentration of 10.0 × 10¹⁰ or more is also preferable. The upper limit is 10.0 × 10¹⁰ １５ The number of particles per mL is often less than or equal to the number of particles per mL. The number of fluorine-containing elastomer particles is the number of particles per 1 mL of aqueous dispersion A. An example of a method for measuring the above number of particles is the measurement method shown in the Examples section.

[0108] The solid content concentration of aqueous dispersion A is preferably 0.01 to 30% by mass. The solid content concentration of the dispersion can be calculated, for example, by heating 2.0 g of the dispersion at 170°C for 20 minutes, weighing the mass of the residue, and using the following formula: "Solid content concentration (mass%) = 100 × Heating residue of dispersion (g) / Mass of dispersion (2.0 g)"

[0109] It is preferable that the fluorine-containing elastomer does not have a melting point. "Having no melting point" means that when the melting point of the fluorine-containing elastomer is measured using a differential scanning calorimeter, no melting peak is observed. Specifically, this means that no melting peak is observed in the temperature range of 150°C or higher (preferably in the temperature range of 150°C to 330°C). Note that the glass transition peak does not fall under the category of a melting peak. Specific methods for measuring the melting point are shown in the Examples section.

[0110] The fluorine-containing elastomer obtained by manufacturing method A is obtained by polymerizing monomer A. The compound (X) used in manufacturing method A may or may not copolymerize with monomer A. The fluorine-containing elastomer may or may not contain structural units based on compound (X).

[0111] The fluorine-containing elastomer obtained by manufacturing method A contains at least TFE units. If monomer A further contains other monomers, the fluorine-containing elastomer obtained by manufacturing method A further contains constituent units based on the other monomers. Details of the other monomers are as described above. The fluorine-containing elastomer obtained by manufacturing method A preferably further contains at least one selected from the group consisting of PAVE units, P units, VdF units, and HFP units, and more preferably further contains PAVE units. The fluorine-containing elastomer may have TFE units and PAVE units, or TFE units and P units, or TFE units, VdF units, and HFP units. When the fluorine-containing elastomer contains TFE units and PAVE units, the TFE unit content in the fluorine-containing elastomer is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE units and PAVE units, from the viewpoint of superior rubber properties. The preferred ratio is the same when the PAVE units are PMVE units (i.e., when the fluorine-containing elastomer contains TFE units and PMVE units) and when the PAVE units are PPVE units (i.e., when the fluorine-containing elastomer contains TFE units and PPVE units). When the fluorine-containing elastomer contains TFE units and P units, the TFE unit content in the fluorine-containing elastomer is preferably 10 to 95 mol%, more preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE units and P units, from the viewpoint of superior rubber properties. When a fluorine-containing elastomer contains TFE units, VdF units, and HFP units, the TFE unit content in the fluorine-containing elastomer is preferably 3 to 60 mol%, more preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE units, VdF units, and HFP units, in order to obtain superior rubber properties.

[0112] (Manufacturing Method B) Manufacturing Method B includes a step of polymerizing a first monomer containing TFE in a first aqueous medium under conditions where emulsifiers and compounds (S11) containing fluorine atoms are substantially absent to produce a first fluorine-containing polymer (hereinafter also referred to as the "first polymerization step"), and a step of polymerizing a second monomer containing TFE in an aqueous dispersion containing the first fluorine-containing polymer to obtain a fluorine-containing elastomer containing the first fluorine-containing polymer and the second fluorine-containing polymer (hereinafter also referred to as the "second polymerization step").

[0113] Manufacturing method B may include other steps as needed. Other steps include, for example, a purification step in which the dispersion containing the first fluorine-containing polymer obtained through the first polymerization step is purified, and a concentration adjustment step in which the solid content concentration of the dispersion containing the first fluorine-containing polymer is adjusted. In manufacturing method B, for example, after the first polymerization step, the process proceeds continuously, after the purification step and concentration adjustment step as needed, before proceeding to the second polymerization step. In manufacturing method B, for example, the first polymerization step, the purification step, the concentration adjustment step, and the second polymerization step are carried out in succession.

[0114] [First Polymerization Step] -Emulsifier- The first polymerization step of manufacturing method B is carried out under conditions in which the emulsifier containing fluorine atoms is substantially absent. Carrying out the first polymerization step under conditions in which the emulsifier is substantially absent is preferable in that it prevents a decrease in the molecular weight of the fluorine-containing elastomer produced. Examples of emulsifiers include the emulsifiers described above. The phrase "substantially absent emulsifier containing fluorine atoms" means that in the first polymerization step, the content of the emulsifier containing fluorine atoms is 10 ppm by mass or less, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less, relative to the total amount of the first aqueous medium. The lower limit is 0 ppb by mass. The phrase "substantially absent emulsifier" means that in the first polymerization step, the content of the emulsifier is 10 ppm by mass or less, relative to the total amount of the first aqueous medium, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less. The lower limit is 0 ppb by mass.

[0115] -First Aqueous Medium- The first polymerization step of manufacturing method B is carried out under conditions in which the first aqueous medium is present. Specific examples of the first aqueous medium are the same as the specific examples of the aqueous medium described above. In this disclosure, "before the polymerization of the first monomer used for polymerization of the first fluorine-containing polymer is started" means immediately before the start of polymerization. Here, "the start of polymerization" refers to the time when the first monomer is added to the reactor after the reactor has been heated to or above the polymerization temperature, and the time when the reactor has been heated to or above the polymerization temperature after the first monomer has been added to the reactor, etc.

[0116] - Compound (X) - The first aqueous medium preferably further contains compound (X). Preferred embodiments of compound (X) are as described above. When compound (X) is contained in the first aqueous medium, the dispersibility of the resulting first fluorine-containing polymer is improved, making polymerization easier, and a first fluorine-containing polymer with a high molecular weight and a large number of particles is obtained. Then, in the second polymerization step which is carried out continuously after the first polymerization step, the large number of particles of the first fluorine-containing polymer that serve as the polymerization site for the second monomer improves the dispersion stability of the second fluorine-containing polymer.

[0117] The amount of compound (X) added is preferably 0.1 to 5000 ppm by mass, more preferably 0.2 to 1000 ppm by mass, even more preferably 0.3 to 500 ppm by mass, and particularly preferably 0.5 to 100 ppm by mass, relative to the total amount of the first aqueous medium.

[0118] -First Monomer- In the first polymerization step of manufacturing method B, a first monomer containing TFE is polymerized. The first monomer may further contain other monomers if the crosslinked rubber contained in the crosslinked rubber article contains constituent units based on the other monomers mentioned above. Details of the other monomers are as described above. In addition to TFE, the first monomer preferably further contains at least one selected from the group consisting of PAVE, propylene, VdF, and HFP units, and more preferably further contains PAVE. The first monomer may contain TFE and PAVE, or TFE and propylene, or TFE, VdF, and HFP. When the first monomer contains TFE and PAVE, the TFE content in the first monomer is 20 to 95 mol%, preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE and PAVE, from the viewpoint of polymerization stability in the second polymerization step. The preferred proportions are the same when PMVE is used as PAVE (i.e., when the first monomer contains TFE and PMVE) and when PPVE is used as PAVE (i.e., when the first monomer contains TFE and PPVE). When the first monomer contains TFE and propylene, the TFE content in the first monomer is 10 to 95 mol%, preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE and propylene, from the viewpoint of polymerization stability in the second polymerization step. When the first monomer contains TFE, VdF and HFP, the TFE content in the first monomer is 3 to 60 mol%, preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE, VdF, and HFP, from the viewpoint of polymerization stability in the second polymerization step. The first monomer may further contain the aforementioned crosslinking monomer. Details of the other monomers and crosslinking monomers are as described above.

[0119] - Chain transfer agent - In the first polymerization step of manufacturing method B, a chain transfer agent may be used. When the crosslinked rubber is a PO-based crosslinked product having a hydrocarbon crosslinked structure, the preferred embodiment of the chain transfer agent is as described above.

[0120] -Polymerization Initiator- In the first polymerization step of manufacturing method B, a polymerization initiator may be used. The preferred embodiment of the polymerization initiator is as described above. The amount of polymerization initiator used is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and even more preferably 0.01 to 2 parts by mass, per 100 parts by mass of the first monomer. When a polymerization initiator is used, it may be added to the reactor all at once or in portions. When added in portions, it may be added in multiple stages or continuously.

[0121] -Polymerization conditions- The polymerization temperature is preferably 10 to 95°C, and more preferably 15 to 90°C. The polymerization pressure is preferably 0.5 to 4.0 MPaG, and more preferably 0.6 to 3.5 MPaG.

[0122] -First Fluorine-containing Polymer- In the first polymerization step of manufacturing method B, for example, by carrying out a step of polymerizing the first monomer, a first aqueous dispersion B1 containing the first fluorine-containing polymer is obtained. The first fluorine-containing polymer contains constituent units based on the first monomer. Compound (X) may or may not be copolymerized with the first monomer. The first fluorine-containing polymer may or may not contain constituent units based on compound (X).

[0123] The first fluorine-containing polymer preferably has no melting point. Having no melting point means that when the melting point of the first fluorine-containing polymer is measured using a differential scanning calorimeter, no melting peak is observed. Specifically, this means that no melting peak is observed in the temperature range of 150°C or higher (preferably in the temperature range of 150°C to 330°C). Note that the glass transition peak does not fall under the category of a melting peak. Specific methods for measuring the melting point are shown in the Examples section.

[0124] The first fluorine-containing polymer obtained in the first polymerization step of manufacturing method B contains at least TFE units. If the first monomer further contains other monomers, the first fluorine-containing polymer further contains constituent units based on the other monomers. Details of the other monomers are as described above. In addition to TFE units, the first fluorine-containing polymer preferably further contains at least one selected from the group consisting of PAVE units, P units, VdF units, and HFP units, and more preferably further contains PAVE units. The first fluorine-containing polymer may have TFE units and PAVE units, or TFE units and P units, or TFE units, VdF units, and HFP units. When the first fluorine-containing polymer contains TFE units and PAVE units, the content of TFE units in the first fluorine-containing polymer is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE units and PAVE units, from the viewpoint of polymerization stability in the second polymerization step. The preferred proportions are the same when PAVE units are PMVE units (i.e., when the first fluorine-containing polymer contains TFE units and PMVE units) and when PAVE units are PPVE units (i.e., when the first fluorine-containing polymer contains TFE units and PPVE units). When the first fluorine-containing polymer contains TFE units and P units, the content of TFE units in the first fluorine-containing polymer is preferably 10 to 95 mol%, more preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE units and P units, from the viewpoint of polymerization stability in the second polymerization step. When the first fluorine-containing polymer has TFE units, VdF units, and HFP units, the content of TFE units in the first fluorine-containing polymer is preferably 3 to 60 mol%, more preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE units, VdF units, and HFP units, from the viewpoint of polymerization stability in the second polymerization step.

[0125] [Purification Step] In the purification step, which may be included in manufacturing method B as needed, the first aqueous dispersion containing the first fluorine-containing polymer obtained through the first polymerization step is subjected to a purification treatment. In the purification step, the first aqueous dispersion obtained through the first polymerization step may be subjected to the purification treatment directly, or the solid content concentration of the first aqueous dispersion may be adjusted by the concentration adjustment step described later before the purification treatment is performed. Manufacturing method B is preferable in that it makes it easier to obtain a second fluorine-containing polymer with desired physical properties. In other words, it is preferable to use the aqueous dispersion after the purification treatment in the above purification step to perform polymerization of the second monomer in the second polymerization step. By going through the purification step, impurities such as polymerization initiators and their decomposition products can be removed, making it easier to obtain a fluorine-containing elastomer with desired physical properties. Examples of purification methods include heat treatment and removal using an ion exchange resin, and a method of contacting the aqueous dispersion to be purified with an ion exchange resin is preferred.

[0126] As the ion exchange resin, a cation exchange resin or an anion exchange resin is preferred. The amount of ion exchange resin used is preferably 1 to 100 parts by mass, and more preferably 1 to 50 parts by mass, per 100 parts by mass of the aqueous dispersion to be purified. Specific examples of methods for contacting the aqueous dispersion to be purified with the ion exchange resin include mixing the aqueous dispersion to be purified with the ion exchange resin or passing the aqueous dispersion to be purified through a column packed with the ion exchange resin. The purification process may be performed multiple times.

[0127] [Concentration Adjustment Step] In the concentration adjustment step, which may be included in manufacturing method B as needed, the solid content concentration of the aqueous dispersion containing the first fluorine polymer may be adjusted. In the concentration adjustment step, for example, at least one of the following is performed on the first aqueous dispersion obtained by the first polymerization step or the aqueous dispersion that has undergone the purification step: removal of an aqueous medium and addition of an aqueous medium. In the concentration adjustment step, the solid content concentration may be adjusted by removing only a portion of the aqueous medium contained in the aqueous dispersion, or solvent substitution may be performed by removing the aqueous medium contained in the aqueous dispersion and adding another aqueous medium. When an aqueous medium is added in the concentration adjustment step, the added aqueous medium may be the same type of aqueous medium as the first aqueous medium, or it may be a different type of aqueous medium.

[0128] [Second Polymerization Step] In the second polymerization step of manufacturing method B, a second monomer containing TFE is polymerized in an aqueous dispersion containing the first fluorine-containing polymer to obtain a fluorine-containing elastomer containing the first fluorine-containing polymer and the second fluorine-containing polymer.

[0129] -Aqueous Dispersion- The aqueous dispersion used in the second polymerization step may be the first aqueous dispersion after the first polymerization step as is, or the first aqueous dispersion after the first polymerization step may have undergone at least one of a purification step and a concentration adjustment step. It is preferable to use an aqueous dispersion in which the first aqueous dispersion after the first polymerization step has undergone at least a purification step, as this makes it easier to obtain a second fluorine-containing polymer with desired physical properties.

[0130] The content of the first fluorine-containing polymer is preferably 0.01 to 10.0% by mass relative to the total amount of the aqueous dispersion, and more preferably 0.01 to 5.0% by mass, as this allows for more efficient production of the second fluorine-containing polymer. In particular, it is preferable that the above range is met before the polymerization of the second monomer begins.

[0131] The aqueous dispersion preferably contains a second aqueous medium. Specific examples of the second aqueous medium are the same as those for the first aqueous medium. The type of the second aqueous medium may be the same as or different from that of the first aqueous medium.

[0132] Before the polymerization of the second monomer begins, the aqueous dispersion may contain other components besides those described above. Specific examples of other components that the aqueous dispersion may contain include chain transfer agents, reducing agents, and pH adjusters. Specific examples of chain transfer agents include ethyl acetate, methanol, ethanol, t-butyl methyl ether, diethyl ether, n-pentane, cyclohexane, methane, 1,4-diiodoperfluorobutane, and propane. Specific examples of pH adjusters include inorganic salts and ammonia. Specific examples of inorganic salts include phosphates such as disodium hydrogen phosphate and sodium dihydrogen phosphate, and carbonates such as sodium bicarbonate and sodium carbonate. More preferred examples of phosphates include disodium hydrogen phosphate dihydrate and disodium hydrogen phosphate dodecahydrate.

[0133] If the aqueous dispersion contains a chain transfer agent, the content of the chain transfer agent is preferably 0.1 to 5 parts by mass per 100 parts by mass of the second aqueous medium. If the aqueous dispersion contains a pH adjusting agent, the content of the pH adjusting agent is preferably 0.01 to 3.0 parts by mass per 100 parts by mass of the second aqueous medium.

[0134] -Second Monomer- The second monomer contains TFE. The second monomer may further contain other monomers if the crosslinked rubber contained in the crosslinked rubber article contains constituent units based on the other monomers described above. Details of the other monomers are as described above. In addition to TFE, the second monomer preferably further contains at least one selected from the group consisting of PAVE, propylene, VdF, and HFP units, and more preferably further contains PAVE. The second monomer may contain TFE and PAVE, or TFE and propylene, or TFE, VdF, and HFP. When the second monomer has TFE and PAVE, the TFE content in the second monomer is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE and PAVE, in order to obtain a polymer with superior rubber properties. The preferred proportions are the same when PMVE is used as PAVE (i.e., when the second monomer contains TFE and PMVE) and when PPVE is used as PAVE (i.e., when the second monomer contains TFE and PPVE). When the second monomer contains TFE and propylene, the TFE content in the second monomer is 10 to 95 mol%, preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE and propylene, in order to obtain a polymer with superior rubber properties. When the second monomer contains TFE, VdF, and HFP, the TFE content in the second monomer is 3 to 60 mol%, preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE, VdF, and HFP, in order to obtain a polymer with superior rubber properties. The second monomer may further contain the aforementioned crosslinking monomer. Details of the other monomers and crosslinking monomers are as described above. The amount of the second monomer used is preferably 1 to 60 parts by mass, more preferably 5 to 50 parts by mass, and even more preferably 10 to 40 parts by mass, per 100 parts by mass of the second aqueous medium.

[0135] - Chain transfer agent - In the second polymerization step of manufacturing method B, a chain transfer agent may be used. When the crosslinked rubber is a PO-based crosslinked product having a hydrocarbon crosslinked structure, the preferred embodiment of the chain transfer agent is as described above.

[0136] -Polymerization Initiator- In the second polymerization step of manufacturing method B, a polymerization initiator may be used. The preferred embodiment of the polymerization initiator is as described above. The amount of polymerization initiator used is preferably 0.01 to 5 parts by mass, more preferably 0.01 to 3 parts by mass, and even more preferably 0.01 to 2 parts by mass, per 100 parts by mass of the amount of the second monomer used. When a polymerization initiator is used, it may be added to the reactor all at once or in portions. When added in portions, it may be added in multiple stages or continuously.

[0137] -Polymerization conditions- The polymerization temperature is preferably 10 to 95°C, and more preferably 15 to 90°C. The polymerization pressure is preferably 0.5 to 4.0 MPaG, and more preferably 0.6 to 3.5 MPaG. The polymerization time is preferably 90 to 1000 minutes, and more preferably 90 to 800 minutes.

[0138] -Emulsifier- The second polymerization step of manufacturing method B is preferably carried out under conditions in which the emulsifier having fluorine atoms is substantially absent. The second polymerization step of manufacturing method B is more preferably carried out under conditions in which the emulsifier is substantially absent. Examples of emulsifiers include the emulsifiers described above. The phrase "substantially absent emulsifier having fluorine atoms" means that in the second polymerization step, the content of the emulsifier having fluorine atoms is 10 ppm by mass or less, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less, relative to the total amount of the second aqueous medium. The lower limit is 0 ppb by mass. The phrase "substantially absent emulsifier" means that in the second polymerization step, the content of the emulsifier is 10 ppm by mass or less, relative to the total amount of the second aqueous medium, preferably 150 ppb by mass or less, and more preferably 50 ppb by mass or less. The lower limit is 0 ppb by mass.

[0139] -Second Fluorine-containing Polymer- In the second polymerization step of manufacturing method B, particles containing the second fluorine-containing polymer are produced. Specifically, the method for producing the second fluorine-containing polymer yields a second aqueous dispersion in which particles containing the second fluorine-containing polymer are dispersed in the aqueous medium. The second fluorine-containing polymer contains structural units based on the second monomer. That is, the second fluorine-containing polymer contains TFE units. If the second monomer further contains other monomers, the second fluorine-containing polymer further contains structural units based on the other monomers. Details of the other monomers are as described above. In addition to TFE units, the second fluorine-containing polymer preferably further contains at least one selected from the group consisting of PAVE units, P units, VdF units, and HFP units, and more preferably further contains PAVE units. The second fluorine-containing polymer may have TFE units and PAVE units, or TFE units and P units, or TFE units, VdF units, and HFP units. When the second fluorine-containing polymer contains TFE units and PAVE units, the TFE unit content in the second fluorine-containing polymer is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE units and PAVE units, from the viewpoint of superior rubber properties. The preferred proportions are the same when PAVE units are PMVE units (i.e., when the second fluorine-containing polymer contains TFE units and PMVE units) and when PAVE units are PPVE units (i.e., when the second fluorine-containing polymer contains TFE units and PPVE units). When the second fluorine-containing polymer contains TFE units and P units, the TFE unit content in the second fluorine-containing polymer is preferably 10 to 95 mol%, more preferably 20 to 85 mol%, and more preferably 25 to 75 mol%, relative to the total content of TFE units and P units, from the viewpoint of superior rubber properties. When the second fluorine-containing polymer contains TFE units, VdF units, and HFP units, the content of TFE units in the second fluorine-containing polymer is preferably 3 to 60 mol%, more preferably 3 to 50 mol%, and more preferably 3 to 40 mol%, relative to the total content of TFE units, VdF units, and HFP units, in order to obtain superior rubber properties.

[0140] -Fluorine-containing elastomer- By carrying out the second polymerization step of manufacturing method B, a fluorine-containing elastomer containing a first fluorine-containing polymer and a second fluorine-containing polymer is obtained. After the second polymerization step of manufacturing method B, for example, a second aqueous dispersion is obtained in which the fluorine-containing elastomer containing the first fluorine-containing polymer and the second fluorine-containing polymer is dispersed in a second aqueous medium.

[0141] In the second aqueous dispersion, the first fluorine-containing polymer and the second fluorine-containing polymer are preferably present in the form of particles. The first fluorine-containing polymer and the second fluorine-containing polymer may be present separately in the second aqueous dispersion, but it is preferable that they are present in the form of particles containing both the first and second fluorine-containing polymers, and more preferably in the form of particles composed of the first and second fluorine-containing polymers (i.e., particles of fluorine-containing elastomers).

[0142] In this case, the average particle size of the fluorine-containing elastomer particles is more preferably 400 nm or less, even more preferably 350 nm or less, and particularly preferably 300 nm or less. The lower limit is preferably 10 nm or more, more preferably 30 nm or more, and even more preferably 50 nm or more. The method for measuring the average particle size of the particles is as described above.

[0143] The fluorine-containing elastomer obtained by manufacturing method B contains at least TFE units. If the crosslinked rubber contained in the crosslinked rubber article further contains constituent units based on the other monomers mentioned above, the fluorine-containing elastomer further contains constituent units based on the other monomers. Details of the other monomers are as described above. The fluorine-containing elastomer obtained by manufacturing method B preferably further contains at least one selected from the group consisting of PAVE units, P units, VdF units, and HFP units, and more preferably further contains PAVE units. The fluorine-containing elastomer obtained by manufacturing method B may have TFE units and PAVE units, or TFE units and P units, or TFE units, VdF units, and HFP units. When the fluorine-containing elastomer obtained by manufacturing method B contains TFE units and PAVE units, the TFE unit content in the fluorine-containing elastomer is preferably 20 to 95 mol%, more preferably 25 to 85 mol%, and more preferably 35 to 75 mol%, relative to the total content of TFE units and PAVE units, in order to obtain superior rubber properties.

[0144] The fluorine-containing elastomer obtained by manufacturing method B preferably has no melting point. Specific methods for measuring the melting point are shown in the Examples section.

[0145] (Agglutination and Separation Process) In the agglutination and separation process, particles of fluorine-containing elastomer are agglutinated in an aqueous dispersion and separated from the aqueous medium. Examples of the aqueous dispersion include aqueous dispersion A obtained by manufacturing method A, and a second aqueous dispersion obtained by manufacturing method B. Examples of the separation method include filtration. Examples of agglutination methods include, but are not limited to, freeze agglutination, acid agglutination, base agglutination, mechanical agglutination, and agglutination using a coagulant.

[0146] A specific example of mechanical coagulation is a method in which shear force is applied by vigorously stirring an aqueous dispersion to coagulate the primary particles of the fluorine-containing elastomer. If necessary, the pH of the aqueous dispersion may be adjusted, or coagulation aids such as electrolytes and water-soluble organic solvents may be added, or the aqueous dispersion may be diluted with water beforehand so that the concentration of the fluorine-containing elastomer in the aqueous dispersion is 8 to 20% by mass. Examples of pH adjusting agents include sodium carbonate and sodium bicarbonate. Mechanical coagulation can also be carried out in the presence of one or more compounds selected from the group consisting of ammonia, ammonium salts, and urea. Examples of electrolytes include inorganic salts such as potassium nitrate, sodium nitrate, sodium carbonate, and sodium bicarbonate. Examples of water-soluble organic solvents include alcohols and acetone.

[0147] For freeze-induced agglutination, the agglutination temperature is preferably -20 to 0°C. The agglutination time is preferably 1 hour or more, and more preferably 2 hours or more. For acid-induced agglutination, a method of adding an acid-containing solution to an aqueous dispersion is preferred. Examples of acids to be added include hydrochloric acid, nitric acid, sulfuric acid, oxalic acid, and hydrofluoric acid, with nitric acid being preferred. The concentration of the acid in the acid-containing solution is preferably 0.1 to 50% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 20% by mass. For base-induced agglutination, a method of adding a base-containing solution to an aqueous dispersion is preferred. Examples of bases to be added include sodium hydroxide, potassium hydroxide, and ammonium carbonate, with sodium hydroxide being preferred. The concentration of the base in the base-containing solution is preferably 0.1 to 50% by mass, more preferably 1 to 30% by mass, and even more preferably 1 to 10% by mass.

[0148] For aggregation using a coagulant, known coagulants can be used. Known coagulants include aluminum salts, calcium salts, magnesium salts, and ammonium salts. Specifically, ammonium carbonate, aluminum sulfate, and the general formula M'Al(SO) ４ ) ２ 12H ２ Examples include alum, calcium nitrate, and magnesium sulfate, represented by O [wherein M' is a monovalent cation other than lithium], with alum being preferred, and potassium alum being more preferred, where M is potassium.

[0149] As described above, in the agglomeration separation step, compound (A) or compound (B) and compound (S11) may be removed. As a method for facilitating the removal of compound (A) or compound (B) and compound (S11) in the agglomeration separation step, for example, a method of performing acid agglomeration or base agglomeration at a temperature below the glass transition temperature of the fluorine-containing elastomer can be mentioned.

[0150] (Mixing step) When the solid composition used for the production of the crosslinked rubber article contains additives such as a crosslinking agent and a filler, in the mixing step, the fluorine-containing elastomer is mixed with the additives such as the crosslinking agent and the filler. The mixing method is not particularly limited, and for example, a kneading method using a known kneading device such as a two-roll mill, a kneader, or a Banbury mixer can be mentioned. The crosslinking agent is selected according to the type of crosslinked structure to be formed. Also, depending on the type of crosslinked structure to be formed, a crosslinking aid may be used as an additive in addition to the crosslinking agent. Additives such as the crosslinking agent and the crosslinking aid are selected according to the type of crosslinked product obtained.

[0151] -CN-based crosslinked product (crosslinked rubber having a heterocyclic crosslinked structure)- A crosslinked rubber article containing a CN-based crosslinked product is produced, for example, using a solid composition containing a fluorine-containing elastomer having a cyano group and a crosslinking agent. By using the above solid composition, in the crosslinking step described later, for example, a crosslinked structure derived from a heterocyclic ring (for example, an oxazole ring) in which a cyano group and a crosslinking agent react, a heterocyclic ring (for example, a triazine ring) in which cyano groups react with each other, etc. is formed.

[0152] Specific examples of the crosslinking agent include a compound having two or more amino groups (hereinafter also referred to as a "polyamine compound"), an organic peroxide, an organic ammonia-generating compound that generates ammonia by heating, and an organotin compound such as an arenyl-tin curing agent. From the viewpoint of obtaining a crosslinked rubber article having excellent crosslinkability of the fluorine-containing elastomer and a smaller compression set, the crosslinking agent is preferably a polyamine compound, and more preferably a compound having two amino groups. <ObjectID=

[0153] The polyamine compound may be a compound in which a hydrogen atom of an aliphatic hydrocarbon is substituted with an amino group, or a compound in which a hydrogen atom of an aromatic hydrocarbon is substituted with an amino group. However, a compound in which a hydrogen atom of an aromatic hydrocarbon is substituted with an amino group is preferred because it exhibits superior rubber properties. The polyamine compound preferably contains a fluorine atom. This improves compatibility with fluorine-containing copolymers, resulting in a crosslinked rubber article with lower compression set at high temperatures.

[0154] Specific examples of polyamine compounds include hexamethylenediamine, hexamethylenediamine carbamate, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (hereinafter also referred to as "BOAP," also known as bisaminophenol AF), 2,2-bis(3,4-diaminophenyl)propane, 2,2-bis(3,4-diaminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-(N-phenylamino)phenyl)hexafluoropropane, 4,4'-methylenedianiline, m-phenylenediamine, adipic acid dihydrazide, and the compound represented by formula (XII) of Japanese Patent No. 5833657, with BOAP being preferred.

[0155] -PO-based crosslinked material (crosslinked rubber having a hydrocarbon crosslinked structure)- A crosslinked rubber article containing a PO-based crosslinked material is manufactured using a solid composition containing, for example, a fluorine-containing elastomer having at least one selected from the group consisting of bromine atoms and iodine atoms, and an organic peroxide that is a crosslinking agent. In addition to the fluorine-containing elastomer and the organic peroxide, the above solid composition may further contain a crosslinking aid. By using the above solid composition, a crosslinked structure derived from, for example, a hydrocarbon group (e.g., alkyl group) is formed in the crosslinking process described later.

[0156] As the organic peroxide which is a crosslinking agent, those having a temperature at which the half-life becomes 1 minute of 100 to 250°C are preferable. Specific examples of the organic peroxide include dialkyl peroxides such as ditert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, α,α-bis(tert-butylperoxy)-p-diisopropylbenzene, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane-3, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxy peroxide, benzoyl peroxide, tert-butyl peroxybenzene, 1,3-bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl 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peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, {tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid , tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-butyl peroxymaleic acid, tert-but​​Specific examples of crosslinking aids include triallyl cyanurate, triallyl isocyanurate (hereinafter also referred to as "TAIC"), trimetallyl isocyanurate, 1,3,5-triacryloylhexahydro-1,3,5-triazine, triallyl trimellitate, m-phenylenediamine bismaleimide, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, dipropargyl terephthalate, diallyl phthalate, N,N',N'',N'''-tetraallyl terephthalamide, vinyl group-containing siloxane oligomers (polymethylvinylsiloxane, polymethylphenylvinylsiloxane, etc.). Among these, triallyl cyanurate, TAIC, and trimetallyl isocyanurate are preferred, with TAIC being more preferred. The amount of crosslinking aid is preferably 0.1 to 10 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of fluorine-containing elastomer. Within this range, the resulting cross-linked rubber articles will have an excellent balance of strength and elongation.

[0158] -Polyol-based crosslinked material (crosslinked rubber having an ether crosslinked structure)- A crosslinked rubber article containing a polyol-based crosslinked material is manufactured using a solid composition containing, for example, a fluorine-containing elastomer having VdF units and a polyol compound that is a crosslinking agent. In addition to the fluorine-containing elastomer and the polyol compound, the solid composition may further contain a crosslinking accelerator, an acid acceptor, etc. By using the solid composition, an ether crosslinked structure is formed in the crosslinking process described later, for example, by the reaction of VdF units and the polyol compound.

[0159] Examples of polyol compounds include polyhydroxyaromatic compounds. Examples of polyhydroxyaromatic compounds include 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis(4-hydroxyphenyl)perfluoropropane (bisphenol AF), resorcinol, 1,3-dihydroxybenzene, 1,7-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxystilbene, 2,6-dihydroxyanthracene, and hydroquinone. Examples include cetones, catechol, 2,2-bis(4-hydroxyphenyl)butane (hereinafter referred to as bisphenol B), 4,4-bis(4-hydroxyphenyl)valeric acid, 2,2-bis(4-hydroxyphenyl)tetrafluorodichloropropane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ketone, tri(4-hydroxyphenyl)methane, 3,3',5,5'-tetrachlorobisphenol A, and 3,3',5,5'-tetrabromobisphenol A. The amount of polyhydroxy aromatic compound blended is 0.1 to 15 parts by mass, preferably 0.5 to 5 parts by mass, per 100 parts by mass of fluorine-containing elastomer.

[0160] Examples of crosslinking accelerators include onium compounds. Examples of onium compounds include ammonium compounds such as quaternary ammonium salts, phosphonium compounds such as quaternary phosphonium salts, oxonium compounds, sulfonium compounds, cyclic amines, and monofunctional amine compounds. The amount of crosslinking accelerator added is preferably 0.01 to 8.00 parts by mass, and more preferably 0.02 to 5.00 parts by mass, per 100 parts by mass of fluorine-containing elastomer.

[0161] Acid acceptors are used to neutralize acidic substances generated during polyol crosslinking. Specific examples include magnesium oxide, calcium hydroxide, calcium oxide, lead oxide, zinc oxide, dibasic lead phosphite, and hydrotalcite.

[0162] -Polyamine-based crosslinked material (crosslinked rubber having an amino crosslink structure)- A crosslinked rubber article containing a polyamine-based crosslinked material is manufactured using a solid composition containing, for example, a fluorine-containing elastomer having VdF units and a polyamine compound as a crosslinking agent. By using the above solid composition, an amino crosslink structure is formed in the crosslinking process described later, for example, by the reaction of VdF units and the polyamine compound. Specific examples of polyamine compounds are the same as the specific examples of polyamine compounds used as crosslinking agents in the manufacture of the CN-based crosslinked material described above.

[0163] (Crosslinking process) In the crosslinking process, the aforementioned solid composition is molded and crosslinked as needed. Crosslinking methods include heating and ionizing radiation. Molding methods include injection molding, extrusion molding, co-extrusion molding, blow molding, compression molding, inflation molding, transfer molding, and calendering.

[0164] When the solid composition contains an organic peroxide as a crosslinking agent, crosslinking by heating is preferred. A specific method for manufacturing crosslinked rubber articles by heating is, for example, the hot press molding method. In the hot press molding method, a heated mold is used, and the solid composition is filled into the cavity of the mold having the desired shape. By heating, crosslinking (hot press crosslinking) is performed simultaneously with molding, thereby obtaining a crosslinked rubber article. The heating temperature is preferably 130 to 220°C, more preferably 140 to 200°C, and even more preferably 150 to 180°C. The heating time can range from 1 second to 24 hours, and is preferably 1 to 20 minutes.

[0165] When using the hot press molding method, it is also preferable to further heat the crosslinked rubber article obtained by hot press crosslinking (hereinafter also referred to as "primary crosslinking") in an oven or the like using electricity, hot air, steam, etc. as a heat source to advance the crosslinking (hereinafter also referred to as "secondary crosslinking"). The temperature during secondary crosslinking is preferably 150 to 280°C, more preferably 180 to 260°C, and even more preferably 200 to 250°C. The secondary crosslinking time is preferably 1 to 48 hours, and more preferably 4 to 24 hours. By performing secondary crosslinking, the rubber properties of the crosslinked rubber article are improved, and the peroxide residue contained in the crosslinked rubber article is decomposed, volatilized, and reduced. The hot press molding method is preferably applied to the molding of sealing materials and the like.

[0166] Examples of ionizing radiation in the ionizing radiation irradiation method include electron beams and gamma rays. When crosslinking by ionizing radiation irradiation, it is preferable to first mold the solid composition into the desired shape and then irradiate it with ionizing radiation to cause crosslinking. Examples of molding methods include applying a suspension solution obtained by dissolving and dispersing the solid composition in a suitable solvent and drying it to form a coating film, or extruding the solid composition to form the shape of a hose or electric wire. The irradiation dose of ionizing radiation is set as appropriate, preferably 1 to 300 kGy, and more preferably 10 to 200 kGy.

[0167] <Applications of Crosslinked Rubber Articles> These crosslinked rubber articles are suitable for use as materials for O-rings, sheets, gaskets, oil seals, diaphragms, V-rings, and the like. Furthermore, this cross-linked rubber material can be used in heat-resistant and chemical-resistant sealing materials, heat-resistant and oil-resistant sealing materials, wire insulation materials, sealing materials for semiconductor manufacturing equipment, sealing materials for liquid crystal display panel manufacturing equipment, sealing materials for light-emitting diode manufacturing equipment, sealing materials for urea-resistant greases, adhesive rubber, hoses, tubes, calender sheets (rolls), sponges, rubber rolls, components for oil drilling, heat dissipation sheets, rubber sponges, bearing seals (urea-resistant, etc.), automotive insulating sheets, insulating sheets for electronic equipment, rubber bands for watches, endoscope packings (amine-resistant), bellows hoses (processed from calender sheets), water heater packings / valves, fenders (marine civil engineering, ships), textiles and nonwoven fabrics (protective clothing, etc.), substrate sealing materials, rubber gloves, stators for single-screw eccentric pumps, components for urea SCR systems, vibration dampers, vibration control agents, sealing agents, additives to other materials, and toys. This cross-linked rubber article is particularly preferred for use as a component in semiconductor manufacturing equipment, and more preferably for use as a sealing material in semiconductor element manufacturing equipment.

[0168] The present invention will be described in detail below with reference to examples. Examples A1, A2, B1, C1, D1, and E1 are examples, and examples A3, A4, B2, C2, D2, and E2 are comparative examples. However, the present invention is not limited to these examples.

[0169] [Measurement Methods and Evaluation Methods] The various measurement and evaluation methods are as follows.

[0170] <Average Particle Size> The aqueous dispersions of each example described below were degassed at 25°C for 5 minutes, pressurized with nitrogen gas to 0.2 MPaG, purged, and returned to atmospheric pressure to obtain the measurement samples. The average particle size of the obtained measurement samples was measured using a dynamic light scattering particle size distribution analyzer (Otsuka Electronics Co., Ltd., ELSZ) with the number of integration cycles set to 100, and this was taken as the average particle size of the particles in each aqueous dispersion.

[0171] <Solid Content Concentration> After heating 2.0 g of the aqueous dispersion of each example described below at 170°C for 20 minutes, the mass (g) of the residue is weighed, and the solid content concentration is calculated using the following formula: Solid Content Concentration (mass%) = 100 × (mass of residue) / (mass of aqueous dispersion (2.0 g))

[0172] <Number of particles in aqueous dispersion> Using the following relationship, x = number of primary particles N × volume of primary particles V × specific gravity of primary particles ρ1 / specific gravity of aqueous dispersion ρ2, the number of primary particles per 1 mL of aqueous dispersion was calculated using the following formula. Primary particles were assumed to be perfect spheres. N = x・ρ2 / (V・ρ1) N (unit: particles / mL): number of primary particles per 1 mL. x (unit: g / g): solid content concentration of aqueous dispersion. V (unit: mL / particle): volume of primary particles, V = 4 / 3・π・(r / 2 × 10) －７ ) ３ r (unit: nm): Average particle size of primary particles. ρ1 (unit: g / mL): Density of primary particles. ρ2 (unit: g / mL): Specific gravity of aqueous dispersion; ρ2 = 1.0 was adopted as an empirically obtained value. x represents the solid content concentration.

[0173] <Proportion of each constituent unit> The proportion of each constituent unit in a fluorine-containing polymer or fluorine-containing elastomer is: １９ The results were obtained from F-NMR analysis and infrared absorption spectroscopy.

[0174] <Melting Point> A 5 ​​mg sample of the obtained fluorine-containing polymer or fluorine-containing elastomer was weighed into an aluminum pan and heated from 20°C to 360°C in an air atmosphere at a heating rate of 10°C / min using a Hitachi DSC600, and the presence or absence of a melting peak was confirmed.

[0175] <Measurement Method for Each Compound Contained in Crosslinked Rubber Articles> (Preparation of Measurement Samples) The crosslinked rubber articles, specifically O-rings, obtained in the examples described below were freeze-dried using a freeze mill, Freezer Mill 6775 (manufactured by SPEX), under the following conditions. Before freeze-drying, 10% by mass of dibutylhydroxytoluene (BHT) was added to the total mass of the O-rings to obtain a pulverized powder. The freeze-drying conditions were: O-ring: 3 g, BHT: 0.3 g, Runtime: 5 min, Rate: 15 cps, Cycle: 3. 2.5 g of the obtained pulverized powder was mixed with 5 mL of methanol and subjected to ultrasonic treatment at 50°C for 2 hours. Centrifugation (5000 rpm, 5 min) was performed to settle the crosslinked bodies of each fluorine-containing elastomer, and the supernatant was used as the extract. The obtained extract was measured by LC / MS / MS. Compound (A) or compound (B) and compound (S11) (hereinafter collectively referred to as "each compound") in the extract were measured using a liquid chromatograph-mass spectrometer. The configuration of the measuring instrument and the LC-MS measurement conditions are shown in Table 1. Using aqueous solutions of each compound with known concentrations, methanol solutions with five or more levels of content were prepared, and LC / MS analysis was performed on the methanol solutions with each content. The relationship between the content and the area area corresponding to that content was plotted, and a calibration curve was drawn. Using the above calibration curve, the area area of ​​the LC / MS chromatogram of each compound in the extract was converted to the content of each compound.

[0176]

[0177] MRM measurement parameters should be appropriately selected according to the structure of each compound being measured. MRM parameters can be obtained using literature values ​​or calculated using an LC-MS instrument. When determining MRM parameters using an LC-MS instrument, the specific procedure is as follows: Using an LC / MS instrument (Shimadzu Corporation, LCMS-8060NX), select product ion search, input the molecular weight of each compound being measured, and perform precursor ion selection, precursor adjustment, voltage optimization, and product m / z optimization. Use the calculated MRM measurement parameters. As an example, the MRM measurement parameters for compounds (S1) to (S4) are shown in Tables 2 to 5. Note that the content of compound (S1) in each extract was determined by converting each compound with p1 = 3 to 13 in formula (S1) to a perfluorocarboxylic acid with the same number of carbon atoms (compound (S2)). Furthermore, the content of compound (S3) in each extract was determined by converting each compound with p3 = 4 to 10 in formula (S3) to a perfluorosulfonic acid (compound (S4)) with the same number of carbon atoms.

[0178]

[0179]

[0180]

[0181]

[0182] (Quantitative determination of each compound contained in cross-linked rubber articles) Specifically, first, methanol standard solutions of each compound with known concentrations from 1 to 180 ng / g were prepared at five different levels. Using a first-order approximation from the sample concentration and the integral value of the peak, a was determined using equation (A1). A = a × X (A1) A: Peak area of ​​each compound, X: Concentration of each compound (ng / g)

[0183] Next, the amount of each compound contained in the extract was calculated using formula (A2). Note that a in formula (A2) is the same as a obtained using formula (A1) above. XCm = ACm / a (A2) XCm: Content of each compound in each extract (ng / g) ACm: Peak area of ​​the compound in each extract Note that the limit of quantification in this measurement is 1 ng / g.

[0184] In the crosslinked rubber article, the content (ZCm) of each compound with respect to the total mass of the crosslinked rubber article was determined by the following formula (A3). ZCm = XCm × ρ1 × La / W1 (A3) ZCm: Content of each compound contained in the crosslinked rubber article ρ1: Density of the extraction solvent (methanol in each example) La: Volume of the extraction solvent (5 mL in each example) W1: Sample mass used for extraction (2.5 g of pulverized powder in each example)

[0185] From the ZCm values of each compound, the content of compound (A), the content of compound (B), the content of (S1), and the content of (S11) in the crosslinked rubber article were determined, respectively.

[0186] <Metal content>A measurement sample obtained by cutting the crosslinked rubber article into appropriate sizes was placed in a platinum crucible and ashed in a high-temperature electric heating furnace, and then sulfuric acid white fuming treatment was performed. Thereafter, it was dissolved in dilute nitric acid. For the solution dissolved in dilute nitric acid, the total content of 29 metal elements (Fe, Na, K, Li, Be, Mg, Al, Ca, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Zr, Mo, Ag, Cd, In, Sn, Cs, Ba, Pb, Bi) was measured by the absolute calibration curve method using an inductively coupled plasma mass spectrometer (ICP-MS 7500cs manufactured by Agilent Technologies).

[0187] <Compression Set of Crosslinked Rubber Articles> The compression set was measured according to the methods described in ASTM D395 or JIS K6262 (2013). The crosslinked rubber articles O-rings (original thickness (wire diameter) = 3.5 mm) prepared in each example were compressed using a compression device by sandwiching the O-ring between two stainless steel plates with a spacer in between, to the compression ratio shown in Table 6. Next, the compression device with the compressed O-ring fixed in place was left in an electric furnace at the compression temperature and time shown in Table 6. After leaving it, the compression device was removed from the electric furnace, the O-ring was immediately removed from the compression device, and the removed O-ring was left in a constant temperature room at 23°C for 30 minutes to measure the thickness of the O-ring (thickness after compression). The test was performed using two O-rings, and the arithmetic mean of the measured values ​​of the two O-rings was used. The compression set was calculated using the following formula. Note that the closer the compression set is to 0%, the smaller the compression set, which is preferable. Compression set (%) = {Original thickness of O-ring (wire diameter) - Thickness of O-ring 30 minutes after removal from compression device (thickness after compression)} ÷ {Original thickness of O-ring (wire diameter) - Thickness of spacer} × 100

[0188]

[0189] [Example A1] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced under conditions where emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent, by the following method. Ultrapure water (1206 g), a 50% by mass aqueous solution of sodium 2-acrylamido-2-methyl-1-propanesulfonate (NaAAMPS, corresponding to "compound (X)") (30 μL, 15 mg of NaAAMPS), PMVE (82 g), and TFE (17 g) were added to a 2.1 L stainless steel pressure reactor, and the temperature was raised to 80°C while stirring at 600 rpm. The reactor pressure at 80°C was 1.4 MPaG. Next, an aqueous solution of ammonium persulfate (2.5% by mass, 7 g) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. This process was repeated until the amount of TFE added after polymerization had started reached 17 g. At that point, 7 g of perfluoro-1,4-diiodobutane (C4DI, 1.08 g) and PMVE were injected. Thereafter, 7 g of PMVE was injected each time 8 g of TFE was injected. When the amount of TFE added after polymerization had started reached 265 g, the addition of TFE and PMVE injected after polymerization had started was stopped, the reactor temperature was cooled to 10°C to stop the polymerization reaction, the remaining gas in the reactor was recovered, and the liquid was withdrawn to obtain an aqueous dispersion A-A1 containing particles of fluorine-containing elastomer A1.

[0190] The total amount of monomers added before polymerization began was 17 g of TFE and 82 g of PMVE. The total amount of monomers added after polymerization began was 265 g of TFE and 217 g of PMVE. The total amount of TFE added was 282 g, and the total amount of PMVE added was 299 g. The average particle size of the fluorine-containing elastomer A1 particles in aqueous dispersion A-A1 was 102.3 nm, and the number of particles of fluorine-containing elastomer A1 was 3.4 × 10⁶. １４The solid content was 28.0% by mass in aqueous dispersion A-A1, with a concentration of 28.0% by mass. After freezing and condensing aqueous dispersion A-A1, it was filtered, and the obtained fluorine-containing elastomer A1 was washed with ultrapure water. Then, it was vacuum-dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer A1 showed a PMVE / TFE ratio of 35 / 65 (molar ratio). Furthermore, fluorine-containing elastomer A1 did not have a melting point.

[0191] <Preparation of Solid Composition> 100 g of the obtained fluorine-containing elastomer A1, 10 g of filler (carbon black, manufactured by Vanderbilt, product name: MT Carbon N990), 5 g of crosslinking aid 1 (manufactured by Nippon Chemical, product name: TAIC-WH60, TAIC60 mass% silica diluted product), 1 g of processing aid (calcium stearate), and 1 g of crosslinking agent 1 (organic peroxide, manufactured by NOF Corporation, compound name: 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) were kneaded together using two rolls at room temperature (25°C) for 10 minutes to obtain a mixture. The gap between the two rolls was adjusted, and the obtained mixture was processed into a 3 mm thick sheet to obtain the solid composition of Example A1.

[0192] <Manufacturing of Crosslinked Rubber Articles> Next, the obtained solid composition was heated and pressed using a hydraulic press (model: SA-301 50T type, manufactured by Tester Sangyo Co., Ltd., ram diameter: 180 mm) at a heating temperature of 150°C for a heating time of 20 minutes to perform primary crosslinking and obtain O-ring 1 (P-26 (standard specified in JIS B2401:2012)). The obtained O-ring 1 was heated in an oven at a secondary crosslinking temperature of 250°C for a secondary crosslinking time of 4 hours to perform secondary crosslinking and obtain O-ring A1, which is a crosslinked rubber article. The crosslinked rubber contained in the obtained O-ring A1 was measured using the method described above and confirmed to have a hydrocarbon crosslinking structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring A1 were measured or evaluated using the method described above. The results are shown in Table 7.

[0193] [Example A2] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced by the following method under conditions in which emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent. (First Polymerization Step) Ultrapure water (1130 g), 30% by mass aqueous ammonia solution (30 mg), PMVE (72 g), and TFE (14 g) were charged into a 2.2 L stainless steel pressure reactor equipped with anchor blades, and the temperature was raised to 90°C while stirring at 600 rpm. Next, ammonium persulfate solution (5.0% by mass, 30 cc) was added and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. After 4 g of TFE was injected under pressure, the reactor was cooled to 10°C and the polymerization reaction was terminated. After recovering the gas remaining in the reactor, the liquid was drained. This liquid was designated as raw material liquid A-A2 (first aqueous dispersion). After freezing and condensing the raw material liquid A-A2, it was filtered, and the resulting first fluorine-containing polymer A2 was analyzed by NMR. The result showed that the PMVE units / TFE units ratio was 30 / 70 (molar ratio).

[0194] (Purification Process) HPR4002Cl (DuPont, anion exchange resin, 200 g) was added to the above raw material solution A-A2. After 150 minutes of stirring, the raw material solution and the anion exchange resin were filtered off. Next, AmberLite® HPR650H (DuPont, cation exchange resin, 50 g) was added to the filtrate. After 60 minutes of stirring, the raw material solution and the cation exchange resin were filtered off to obtain raw material solution B-A2. In raw material solution B-A2, particles of the first fluorine-containing polymer A2 were dispersed in an aqueous medium, and the content of the first fluorine-containing polymer A2 was 0.6% by mass of the total mass of raw material solution B-A2.

[0195] (Concentration adjustment step, second polymerization step) A stainless steel pressure reactor with an internal volume of 2.2 L equipped with anchor blades was charged with raw material liquid B-A2 (1000 g) and ultrapure water (175 g) to obtain aqueous dispersion B-A2. The content of the first fluorine-containing polymer A2 was 0.4% by mass relative to the total mass of aqueous dispersion B-A2. Perfluoro-1,4-diiodobutane (C4DI, 2.0 g), PMVE (72 g), and TFE (14 g) were charged into the aqueous dispersion B-A2, and the temperature was raised to 80°C while stirring at 600 rpm. TFE and PMVE were injected under pressure until the reactor pressure reached 1.2 MPa [gauge], and an aqueous solution of ammonium persulfate (APS aqueous solution, 1.0% by mass, 20 mL) was added to start polymerization. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. After injecting 160g of TFE and 133g of PMVE under pressure, the reactor was cooled to 10°C to terminate the polymerization reaction. After recovering the gas remaining in the reactor after the polymerization reaction was complete, the liquid was removed from the reactor. This liquid was designated as the second aqueous dispersion A2.

[0196] The second aqueous dispersion A2 was a dispersion in which particles (average particle size 92.7 nm) containing the first fluorine-containing polymer A2 and the second fluorine-containing polymer A2, were dispersed in an aqueous medium, and the solid content concentration was 20.5% by mass. The second aqueous dispersion A2 was freeze-coagulated and then filtered, and the obtained fluorine-containing elastomer A2 was washed with ultrapure water. After that, it was vacuum-dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer A2 showed a PMVE / TFE ratio of 35 / 65 (molar ratio). Furthermore, the fluorine-containing elastomer A2 did not have a melting point.

[0197] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition A2 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer A2 was used instead of fluorine-containing elastomer A1. O-ring A2 was obtained in the same manner as in Example A1, except that solid composition A2 was used instead of solid composition A1. The crosslinked rubber contained in the obtained O-ring A2 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring A2 were measured or evaluated using the method described above. The results are shown in Table 7.

[0198] [Example A3] <Production of Fluorine-Containing Elastomer> Under conditions where neither the emulsifier without fluorine atoms nor the compound (S11) is substantially present, a fluorine-containing elastomer was produced using the emulsifier A described below, which corresponds to compound (S6) as an emulsifier containing fluorine atoms. After degassing a 2.2 L stainless steel pressure reactor equipped with anchor blades, ultrapure water (1004 g) and the emulsifier C were added. ２ F ５ OCF ２ CF ２ OCF ２ COONH ４A 30% aqueous solution of (emulsifier A) (80.1 g), a 5% aqueous solution of disodium hydrogen phosphate dodecahydrate (10.49 g), and perfluoro-1,4-diiodobutane (C4DI, 1.0 g) were charged, and the gas phase was purged with nitrogen. While stirring at a speed of 600 rpm using an anchor blade, PMVE (72 g) and TFE (14 g) were injected into the container under pressure, and the internal temperature was raised to 80°C. Next, an aqueous solution of APS (1.0% by mass, 20 ml) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE and PMVE were added to maintain a constant pressure of 1.2 MPa [gauge]. After 160 g of TFE and 133 g of PMVE were injected under pressure, the reactor was cooled to 10°C, and the polymerization reaction was terminated. After recovering the gas remaining in the reactor following the polymerization reaction, the liquid was removed from the reactor. This liquid was designated as aqueous dispersion A-A3. Aqueous dispersion A-A3 was a dispersion in which particles containing fluorine-containing elastomer A3 (average particle size 84 nm) were dispersed in an aqueous medium, with a solid content concentration of 21.1% by mass. The obtained dispersion was added to an aqueous solution of potassium aluminum sulfate to induce coagulation. After drying, fluorine-containing elastomer A3 was obtained. NMR analysis of the obtained fluorine-containing elastomer A3 showed a PMVE / TFE ratio of 35 / 66 (molar ratio).

[0199] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition A3 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer A3 was used instead of fluorine-containing elastomer A1. O-ring A3 was obtained in the same manner as in Example A1, except that solid composition A3 was used instead of solid composition A1. The crosslinked rubber contained in the obtained O-ring A3 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring A3 were measured or evaluated using the method described above. The results are shown in Table 7.

[0200] [Example A4] <Production of Fluorine-Containing Elastomer> Under conditions where neither the emulsifier containing fluorine atoms nor the compound (S11) is substantially present, a hydrocarbon polymer (polymethyl methacrylate) was used as the emulsifier that does not contain fluorine atoms, and a fluorine-containing elastomer was produced by the following method. (First Polymerization Step) Ultrapure water (593 g) and MMA (methyl methacrylate, 2.8 g) were charged into a 1.0 L glass reactor and the temperature was raised to 60°C while stirring at 500 rpm. Next, an aqueous solution of ammonium persulfate (10% by mass, 6.0 cc) was added and polymerization was carried out for 60 minutes. After the polymerization reaction was completed, the liquid was removed and this liquid was designated as raw material liquid A-A4.

[0201] (Purification Process) Purolite A300 (anion exchange resin, manufactured by Purolite, 20 g) was added to the above raw material solution A-A4 (490 g). After 60 minutes of stirring, the raw material solution and the anion exchange resin were filtered off to obtain raw material solution B-A4. Raw material solution B-A4 contained hydrocarbon polymer (poly MMA) particles (average particle size 116 nm) dispersed in an aqueous medium. Based on the amount of MMA charged, the hydrocarbon polymer content was 0.47% by mass of the total mass of raw material solution B-A4.

[0202] (Second Polymerization Process) In a 2.2 L stainless steel pressure reactor equipped with anchor blades, the raw material liquid B-A4 (3.91 g), ultrapure water (1162 g), and perfluoro-1,4-diiodobutane (C4DI, 2.0 g) were charged to obtain an aqueous dispersion B-A4. The aqueous dispersion B-A4 was heated to 80°C while being stirred at 600 rpm, and PMVE (72 g) and TFE (14 g) were charged thereto. Next, an aqueous solution of ammonium persulfate (20% by mass, 5 mL) was added to start polymerization. As the pressure inside the reactor decreased as polymerization began, TFE and PMVE were further added to maintain a constant pressure of 1.2 MPa [gauge]. After 160 g of TFE and 133 g of PMVE were injected under pressure, the reactor was cooled and the polymerization reaction was terminated. The polymerization time was 411 minutes. After recovering the remaining gas in the reactor, the liquid was removed. This liquid was designated as the second aqueous dispersion A4.

[0203] The second aqueous dispersion A4 was a dispersion in which particles containing fluorine-containing elastomer A4 (average particle size 195.2 nm) were dispersed in an aqueous medium, and the solid content concentration was 20.7% by mass. After freezing and agglomerating the second aqueous dispersion A4, it was filtered off, and the obtained fluorine-containing elastomer A4 was washed with ultrapure water. Then, it was vacuum dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer A4 showed a PMVE / TFE ratio of 34 / 66 (molar ratio). Furthermore, fluorine-containing elastomer A4 did not have a melting point.

[0204] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Articles> Solid composition A4 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer A4 was used instead of fluorine-containing elastomer A1. O-ring A4 was obtained in the same manner as in Example A1, except that solid composition A4 was used instead of solid composition A1. The crosslinked rubber contained in the obtained O-ring A4 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring A4 were measured or evaluated using the method described above. The results are shown in Table 7. Note that in Example A4, compound (A), compound (B), and compound (S11) were not used in the manufacturing process of fluorine-containing elastomer A4. However, since polymethyl methacrylate, an emulsifier that does not contain fluorine atoms, was used as an emulsifier, it is presumed that compound (S1) was produced as a by-product in the manufacturing process of fluorine-containing elastomer A4, resulting in a high (S1) content.

[0205] [Example B1] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced under conditions where emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent, by the following method. Ultrapure water (1206 g), a 50% by mass aqueous solution of sodium 2-acrylamido-2-methyl-1-propanesulfonate (NaAAMPS, corresponding to "compound (X)") (30 μL, 15 mg of NaAAMPS), C3DVE (1.64 g), PMVE (82 g), and TFE (17 g) were added to a 2.1 L stainless steel pressure reactor, and the temperature was raised to 80°C while stirring at 600 rpm. The reactor pressure at 80°C was 1.4 MPaG. Next, an aqueous solution of ammonium persulfate (2.5% by mass, 7 g) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. This process was repeated until the amount of TFE added after polymerization had started reached 17 g. At that point, perfluoro-1,4-diiodobutane (C4DI, 1.52 g) and PMVE (7 g) were injected under pressure. Thereafter, 7 g of PMVE was injected every time 8 g of TFE was injected under pressure. When the amount of TFE added after polymerization had started reached 265 g, the addition of TFE and PMVE injected under pressure after polymerization had started was stopped, the reactor temperature was cooled to 10°C to stop the polymerization reaction, the remaining gas in the reactor was recovered, and the liquid was drained to obtain aqueous dispersion A-B1 containing particles of fluorine-containing elastomer B1.

[0206] The total amount of monomers added before polymerization began was 17 g of TFE and 82 g of PMVE. The total amount of monomers added after polymerization began was 265 g of TFE and 217 g of PMVE. The total amount of TFE added was 282 g, and the total amount of PMVE added was 299 g. The average particle size of the fluorine-containing elastomer B1 particles in aqueous dispersion A-B1 was 98.1 nm, and the number of particles of fluorine-containing elastomer B1 was 3.9 × 10⁻⁶. １４The solid content was 28.4% by mass in aqueous dispersion A-B1, with a concentration of 28.4% by mass. After freezing and condensing aqueous dispersion A-B1, it was filtered, and the obtained fluorine-containing elastomer B1 was washed with ultrapure water. It was then vacuum-dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer B1 showed a PMVE / TFE ratio of 33 / 67 (molar ratio). Furthermore, fluorine-containing elastomer B1 did not have a melting point.

[0207] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition B1 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer B1 was used instead of fluorine-containing elastomer A1, the amount of filler added was changed from 10 g to 15 g, and the amount of crosslinking aid 1 added was changed from 5 g to 3 g. O-ring B1 was obtained in the same manner as in Example A1, except that solid composition B1 was used instead of solid composition A1. The crosslinked rubber contained in the obtained O-ring B1 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring B1 were measured or evaluated using the method described above. The results are shown in Table 7.

[0208] [Example B2] <Production of Fluorine-Containing Elastomer> Under conditions where neither the emulsifier without fluorine atoms nor compound (S11) is substantially present, a fluorine-containing elastomer was produced using the emulsifier A, which corresponds to compound (S6) as an emulsifier containing fluorine atoms, by the method described below. Polymerization was carried out in the same manner as in Example A3, except that C3DVE (1.6 g) was further added before raising the internal temperature of the container to 80°C, to obtain aqueous dispersion A-B2. Aqueous dispersion A-B2 was a dispersion in which particles (average particle size 75 nm) containing fluorine-containing elastomer B2 were dispersed in an aqueous medium, and the solid content concentration was 21.0% by mass. The obtained dispersion was added to an aqueous solution of potassium aluminum sulfate and allowed to solidify. After drying, fluorine-containing elastomer B2 was obtained. NMR analysis of the obtained fluorine-containing elastomer B2 showed a PMVE / TFE ratio of 34 / 66 (molar ratio).

[0209] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition B2 was obtained in the same manner as in Example B1, except that the obtained fluorine-containing elastomer B2 was used instead of fluorine-containing elastomer B1. O-ring B2 was obtained in the same manner as in Example B1, except that solid composition B2 was used instead of solid composition B1. The crosslinked rubber contained in the obtained O-ring B2 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring B2 were measured or evaluated using the method described above. The results are shown in Table 7.

[0210] [Example C1] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced under conditions where emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent, by the following method. Ultrapure water (1206 g), a 50% by mass aqueous solution of sodium 2-acrylamido-2-methyl-1-propanesulfonate (NaAAMPS, corresponding to "compound (X)") (30 μL, 15 mg of NaAAMPS), C3DVE (1.06 g), PMVE (82 g), and TFE (17 g) were added to a 2.1 L stainless steel pressure reactor, and the temperature was raised to 80°C while stirring at 380 rpm. The reactor pressure at 80°C was 1.4 MPaG. Next, an aqueous solution of ammonium persulfate (2.5% by mass, 7 g) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. This process was repeated until the amount of TFE added after polymerization had started reached 17 g. At that point, perfluoro-1,4-diiodobutane (C4DI, 0.42 g) and PMVE (8 g) were injected under pressure. Thereafter, 8 g of PMVE was injected every time 11 g of TFE was injected under pressure. When the amount of TFE added after polymerization had started reached 162 g, the addition of TFE and PMVE injected under pressure after polymerization had started was stopped, the reactor temperature was cooled to 10°C to stop the polymerization reaction, the remaining gas in the reactor was recovered, and the liquid was withdrawn to obtain an aqueous dispersion A-C1 containing particles of fluorine-containing elastomer C1.

[0211] The total amount of monomers added before polymerization began was 17 g of TFE and 82 g of PMVE. The total amount of monomers added after polymerization began was 162 g of TFE and 95 g of PMVE. The total amount of TFE added was 179 g, and the total amount of PMVE added was 177 g. The average particle size of the fluorine-containing elastomer C1 particles in aqueous dispersion A-C1 was 80.7 nm, and the number of particles of fluorine-containing elastomer C1 was 3.9 × 10⁶. １４ The solid content was 17.8% by mass in aqueous dispersion A-C1, with a concentration of 17.8% by mass. After freezing and condensing aqueous dispersion A-C1, it was filtered, and the obtained fluorine-containing elastomer C1 was washed with ultrapure water. Then, it was vacuum-dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer C1 showed a PMVE / TFE ratio of 30 / 70 (molar ratio). Furthermore, fluorine-containing elastomer C1 did not have a melting point.

[0212] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Articles> Solid composition C1 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer C1 was used instead of fluorine-containing elastomer A1, no fillers or processing aids were added, and 0.5 g of crosslinking aid 2 (manufactured by Nippon Chemical, product name: TAIC, TAIC 100% by mass) was added instead of 5 g of crosslinking aid 1. O-ring C1 was obtained in the same manner as in Example A1, except that solid composition C1 was used instead of solid composition A1, and the heating time during primary crosslinking was changed from 20 minutes to 10 minutes. The crosslinked rubber contained in the obtained O-ring C1 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring C1 were measured or evaluated using the method described above. The results are shown in Table 7.

[0213] [Example C2] <Production of fluorine-containing elastomer> Under conditions where neither the emulsifier without fluorine atoms nor compound (S11) is substantially present, a fluorine-containing elastomer was produced using the emulsifier A described below, which corresponds to compound (S6) as an emulsifier containing fluorine atoms. Ultrapure water (8270g) and emulsifier C were placed in a 20L stainless steel pressure reactor. ２ F５ OCF ２ CF ２ OCF ２ COONH ４ A 30% aqueous solution of (emulsifier A) (733 g), a 5% aqueous solution of disodium hydrogen phosphate dodecahydrate (15.9 g), perfluoro-1,4-diiodobutane (C4DI, 7.0 g), and C3DVE (10.0 g) were charged, and the gas phase was purged with nitrogen. While stirring at a speed of 375 rpm using an anchor blade, PMVE (454 g) and TFE (198 g) were injected into the container under pressure, and the internal temperature was raised to 80°C. Next, an aqueous solution of APS (1.0% by mass, 40 ml) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE and PMVE were added to maintain a constant pressure of 0.943 MPa [gauge]. After 1200 g of TFE and 868 g of PMVE were injected under pressure, the reactor was cooled, and the polymerization reaction was terminated. The polymerization time was 270 minutes. After recovering the gas remaining in the reactor, the liquid was withdrawn to obtain an aqueous dispersion A-C2 in which particles containing fluorine-containing elastomer C2 were dispersed in an aqueous medium. After freezing and condensing aqueous dispersion A-C2, it was filtered, and the obtained fluorine-containing elastomer C2 was washed with ultrapure water. Then, it was vacuum dried at 100°C. NMR analysis of the obtained fluorine-containing elastomer C2 showed a PMVE / TFE ratio of 28 / 72 (molar ratio). Furthermore, fluorine-containing elastomer C2 did not have a melting point.

[0214] <Manufacture of Solid Composition and Crosslinked Rubber Article> Solid composition C2 was obtained in the same manner as in Example C1, except that the obtained fluorine-containing elastomer C2 was used instead of fluorine-containing elastomer C1. O-ring C2 was obtained in the same manner as in Example C1, except that solid composition C2 was used instead of solid composition C2. The crosslinked rubber contained in the obtained O-ring C2 was measured using the method described above, and it was confirmed that it had a hydrocarbon crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring C2 were measured or evaluated using the method described above. The results are shown in Table 7.

[0215] [Example D1] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced by the following method under conditions in which emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent. A 2.2 L stainless steel pressure reactor contained ultrapure water (1206 L), a 50% by mass aqueous solution (30 μL) of sodium 2-acrylamido-2-methyl-1-propanesulfonate (NaAAMPS, corresponding to "compound (X)"), PMVE (81 g), TFE (17 g), and CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ 3.4 g of CN (8CNVE) was added and the temperature was raised to 80°C. The reactor pressure at 80°C was 1.4 MPaG. Next, 7 g of ammonium persulfate aqueous solution (2.5% by mass) was added and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE was added to maintain a constant pressure. While intermittently adding ammonium persulfate aqueous solution, 12 g of PMVE and 1.26 g of 8CNVE were added each time 16 g of TFE was injected. When the amount of TFE added after polymerization had started reached 160 g, the addition of TFE, PMVE, and 8CNVE after polymerization had started was stopped, the reactor temperature was cooled to 10°C to stop the polymerization reaction, the remaining gas in the reactor was recovered, and the liquid was withdrawn to obtain aqueous dispersion A-D1.

[0216] The total amount of TFE added before polymerization was 17 g, and the total amount of PMVE added was 82 g. The total amount of TFE added after polymerization was 160 g, and the total amount of PMVE added was 108 g. The total amount of TFE added was 177 g, the total amount of PMVE added was 190 g, and the total amount of 8CNVE added was 16.0 g. The average particle size of the fluorine-containing elastomer D1 particles in aqueous dispersion A-D1 was 70.2 nm. The solid content concentration of aqueous dispersion A-D1 was 21.0% by mass. Aqueous dispersion A-D1 was coagulated with a 5% by mass aqueous nitric acid solution, filtered, and the obtained solid was washed with ultrapure water. Then, it was vacuum dried at 100°C for 12 hours to obtain fluorine-containing elastomer D1. NMR analysis of the obtained fluorine-containing elastomer D1 revealed that its composition was PMVE / TFE / 8CNVE = 31.0 / 68.4 / 0.6 (molar ratio). Furthermore, fluorine-containing elastomer D1 did not have a melting point.

[0217] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Articles> Solid composition D1 was obtained in the same manner as in Example A1, except that the obtained fluorine-containing elastomer D1 was used instead of fluorine-containing elastomer A1, the amount of filler added was changed from 10 g to 5 g, crosslinking aid 1 and processing aid were not added, and 0.8 g of crosslinking agent 2 (BOAP, polyamine compound) was added instead of 1 g of crosslinking agent 1. O-ring D1 was obtained in the same manner as in Example A1, except that solid composition D1 was used instead of solid composition A1, the heating temperature during primary crosslinking was changed from 150°C to 180°C, and secondary crosslinking was performed as follows. Specifically, secondary crosslinking was performed by heating the O-ring 1 that had undergone primary crosslinking in an oven (DN411I, manufactured by Yamato Scientific Co., Ltd.) in a nitrogen atmosphere at 90°C for 2 hours, then raising the temperature to 200°C over 2 hours and heating at 200°C for 4 hours, and then raising the temperature to 305°C over 2 hours and heating at 305°C for 12 hours. Subsequently, the O-ring was cooled to 23°C to obtain O-ring D1, a crosslinked rubber article. The crosslinked rubber contained in the obtained O-ring D1 was measured using the method described above, and it was confirmed to have a heterocyclic crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring D1 were measured or evaluated using the method described above. The results are shown in Table 8.

[0218] [Example D2] <Production of fluorine-containing elastomer> Under conditions where neither the emulsifier without fluorine atoms nor compound (S11) is substantially present, a fluorine-containing elastomer was produced using the emulsifier A described below, which corresponds to compound (S6) as an emulsifier containing fluorine atoms. After degassing a 2.2 L stainless steel pressure reactor equipped with anchor blades, ultrapure water (1053 g) and the emulsifier C were added. ２ F ５ OCF ２ CF ２ OCF ２ COONH ４ (Emulsifier A) 30% by mass aqueous solution (129 g), disodium hydrogen phosphate dodecahydrate (0.113 g), CF ２ = CFOCF ２ CF (CF ３ ) OCF２ CF ２ CN(8CNVE) (1.1g) was added, and the gas phase was purged with nitrogen. While stirring at a speed of 600 rpm using an anchor blade, PMVE (72g) and TFE (14g) were injected into the container under pressure, and the internal temperature was raised to 80°C. Next, an aqueous APS solution (3.0% by mass, 18 ml) was added, and polymerization was started. As polymerization began, the pressure inside the reactor decreased, so TFE and PMVE were added to maintain a constant pressure of 0.918 MPa [gauge]. After injecting 160g of TFE and 108g of PMVE, the reactor was cooled to 10°C to stop the polymerization reaction, the remaining gas in the reactor was recovered, and the liquid was withdrawn to obtain aqueous dispersion A-D2. The average particle size of the fluorine-containing elastomer D2 particles in aqueous dispersion A-D2 was 27.9 nm, and the solid content concentration of aqueous dispersion A-D2 was 20.1% by mass. Aqueous dispersion A-D2 was coagulated with a 5% by mass aqueous nitric acid solution, filtered, and the obtained solid was washed with ultrapure water. Then, it was vacuum dried at 100°C for 12 hours to obtain fluorine-containing elastomer D2. NMR analysis of the obtained fluorine-containing elastomer D2 revealed that its composition was PMVE / TFE / 8CNVE = 29.6 / 69.7 / 0.7 (molar ratio). Furthermore, fluorine-containing elastomer D2 did not have a melting point.

[0219] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition D2 was obtained in the same manner as in Example D1, except that the obtained fluorine-containing elastomer D2 was used instead of fluorine-containing elastomer D1. O-ring D2 was obtained in the same manner as in Example D1, except that solid composition D2 was used instead of solid composition D1. The crosslinked rubber contained in the obtained O-ring D2 was measured using the method described above, and it was confirmed that it has a heterocyclic crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring D2 were measured or evaluated using the method described above. The results are shown in Table 8.

[0220] [Example E1] <Production of Fluorine-Containing Elastomer> A fluorine-containing elastomer was produced under conditions where emulsifiers containing fluorine atoms, emulsifiers not containing fluorine atoms, and compound (S11) were substantially absent, by the following method. Polymerization was carried out in the same manner as in Example D1, except that an additional 3.2 g of C3DVE was added before raising the temperature to 80°C, to obtain aqueous dispersion A-E1. The total amount of TFE added was 177 g, the total amount of PMVE added was 190 g, the total amount of 8CNVE added was 16.0 g, and the total amount of C3DVE added was 3.2 g. The average particle size of the fluorine-containing elastomer E1 particles in aqueous dispersion A-E1 was 80.0 nm, and the solid content concentration of aqueous dispersion A-E1 was 22.0% by mass. Aqueous dispersion A-E1 was coagulated with a 5% by mass aqueous nitric acid solution, filtered, and the obtained solid was washed with ultrapure water. Subsequently, the material was vacuum-dried at 100°C for 12 hours to obtain fluorine-containing elastomer E1. NMR analysis of the obtained fluorine-containing elastomer E1 revealed a composition of PMVE / TFE / 8CNVE = 30.6 / 68.8 / 0.6 (molar ratio). Furthermore, fluorine-containing elastomer E1 did not have a melting point.

[0221] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition E1 was obtained in the same manner as in Example D1, except that the obtained fluorine-containing elastomer E1 was used instead of fluorine-containing elastomer D1. O-ring E1 was obtained in the same manner as in Example D1, except that solid composition E1 was used instead of solid composition D1. The crosslinked rubber contained in the obtained O-ring E1 was measured using the method described above, and it was confirmed that it has a heterocyclic crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring E1 were measured or evaluated using the method described above. The results are shown in Table 8.

[0222] [Example E2] <Production of Fluorine-Containing Elastomer> Under conditions where neither the emulsifier without fluorine atoms nor compound (S11) is substantially present, a fluorine-containing elastomer was produced using emulsifier A, which corresponds to compound (S6) as an emulsifier containing fluorine atoms, by the following method. Polymerization was carried out in the same manner as in Example D2, except that 3.2 g of C3DVE was added before raising the temperature to 80°C, to obtain aqueous dispersion A-E2. The average particle size of the particles of fluorine-containing elastomer E2 in aqueous dispersion A-E2 was 30.0 nm, and the solid content concentration of aqueous dispersion A-E2 was 20.2% by mass. Aqueous dispersion A-E2 was coagulated with a 5% by mass aqueous nitric acid solution, filtered, and the obtained solid was washed with ultrapure water. Then, it was vacuum dried at 100°C for 12 hours to obtain fluorine-containing elastomer E2. NMR analysis of the obtained fluorine-containing elastomer E2 revealed that its composition was PMVE / TFE / 8CNVE = 29.6 / 69.8 / 0.6 (molar ratio). Furthermore, the fluorine-containing elastomer E2 did not have a melting point.

[0223] <Manufacture of Solid Composition, Manufacture of Crosslinked Rubber Article> Solid composition E2 was obtained in the same manner as in Example D1, except that the obtained fluorine-containing elastomer E2 was used instead of fluorine-containing elastomer D1. O-ring E2 was obtained in the same manner as in Example D1, except that solid composition E2 was used instead of solid composition D1. The crosslinked rubber contained in the obtained O-ring E2 was measured using the method described above, and it was confirmed that it has a heterocyclic crosslinked structure. Furthermore, the compound (A) content, compound (B) content, (S1) content, (S11) content, metal content, and compression set of the obtained O-ring E2 were measured or evaluated using the method described above. The results are shown in Table 8.

[0224]

[0225]

[0226] In Tables 7 and 8, "-" indicates that the corresponding component was not added. As shown in Tables 7 and 8, in Examples A1 and A2, crosslinked rubber articles with smaller compression set were obtained compared to Examples A3 and A4. Similarly, in Examples B1, C1, D1, and E1, crosslinked rubber articles with smaller compression set were obtained compared to Examples B2, C2, D2, and E2, respectively.

[0227] The disclosure of Japanese Patent Application No. 2025-009396, filed on 22 January 2025, is incorporated herein by reference in its entirety. Furthermore, all documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually indicated as being incorporated by reference.

Claims

1. A crosslinked rubber article containing a crosslinked rubber containing a structural unit based on tetrafluoroethylene, wherein the crosslinked rubber article contains none of the compounds represented by formula (S1), formula (S2), formula (S3), formula (S4), formula (S5), formula (S6), formula (S7), formula (S8), formula (S9), and formula (S10), or contains at least one selected from the group consisting of the compounds (S1) to (S10) and the total content of the compounds (S1) to (S10) is 10,000 mass ppb or less with respect to the crosslinked rubber article, does not contain the compound (S1), or contains the compound (S1) and the total content of the compound (S1) is 1,000 mass ppb or less with respect to the crosslinked rubber article, does not contain the compound represented by formula (S11), or contains the compound (S11) and the total content of the compound (S11) is 1,000 mass ppb or less with respect to the crosslinked rubber article. H(CF ２ ) ｐ１ COOM １ (S1) H(CF ２ ) ｐ２ SO ３ M ２ (S2) F(CF ２ ) ｐ３ COOM ３ (S3) F(CF ２ ) ｐ４ SO ３ M ４ (S4) X ５１ (CF ２ ) ｐ５ (OCF ２ CF ２ CF ２ ) ｑ５ OCF(X ５２ )CF ２ COOM ５ (S5) X ６１ (CF ２ ) ｐ６ (OCF(X ６２ ) CF(X ６３ )) ｑ６ OCF(X ６４ ) COOM ６ (S6) X ７１ (CF ２ ) ｐ７ CF(X ７２ ) (OCF(X ７３ ) CF(X ７４ )) ｑ７ OCF(X ７５ ) COOM ７ (S7) X １０１ CF ２ (OCF ２ CF ２ ) ｑ１０ (OCF ２ ) ｒ１０ X １０２ (S10) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formulas (S1) to (S11), M １ ~M ９ Each is independently a hydrogen atom, Na, K, or NH ４ X ５１ , X ６１ , X ７１ , X ８１ , X ８２ , X ９１ , and X ９２ Each of these is independently a hydrogen atom, a fluorine atom, or a chlorine atom, and X １０１ and X １０２ Each of these is independently a hydrogen atom, a fluorine atom, a COOH group, or a chlorine atom, and X １０１ and X １０２ At least one of them is COOH, X ５２ , X ６２ ~X ６４ , and X ７２ ~X ７５ Each of these is independently a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms, and Rf ８ ~Rf ９ Each of these is independently a fluorine-containing alkylene group having 1 to 20 carbon atoms, and X １１１ and X １１２ Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 and p3 are independently integers from 3 to 13, p2 and p4 are independently integers from 4 to 10, p5 to p7 are independently integers from 1 to 10, q5 to q7 are independently integers from 0 to 3, q8 to q9 are independently integers from 1 to 20, n8 to n9 are independently integers from 1 to 30, and q8 and n8 are the CF contained in compound (S8). ２ A combination of integers such that the number of elements is 30 or less, where q9 and n9 are the CFs of the compound (S9). ２ The integer combinations are such that the number of groups is 30 or less, where q10, r10, q11, and r11 are each independent integers of 0 or greater, where q10 and r10 are integer combinations such that the number average molecular weight of compound (S10) is between 300 and 2000, and q11 and r11 are integer combinations such that the number average molecular weight of compound (S11) is between 300 and 2000.

2. A crosslinked rubber article containing a crosslinked rubber containing a structural unit based on tetrafluoroethylene, having one or more CF ２ groups and one or more ionic functional groups, wherein the ionic functional group is COOM, SO ３ M, PO ４ M, or SO ４ M, where M is a hydrogen atom, Na, K, or NH ４ , and the number of CF ２ groups per ionic functional group is 30 or less, having no carbon-carbon double bond and no carbon-carbon triple bond, and when a compound having a number average molecular weight of 3000 or less is defined as compound (B), the crosslinked rubber article either does not contain compound (B) or contains compound (B) with a total content thereof of 10,000 mass ppb or less with respect to the crosslinked rubber article, does not contain a compound (S1) represented by formula (S1) among compound (B) or contains compound (S1) with a total content thereof of 1000 mass ppb or less with respect to the crosslinked rubber article, and does not contain a compound (S11) represented by formula (S11) which is a compound other than compound (B) or contains compound (S11) with a total content thereof of 1000 mass ppm or less with respect to the crosslinked rubber article. H(CF ２ ) ｐ１ COOM １ (S1) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formulae (S1) and (S11), M １ is a hydrogen atom, Na, K, or NH ４ , X １１１ and X １１２ are each independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 is an integer from 3 to 13, q11 and r11 are each independently an integer of 0 or more, and q11 and r11 are a combination of integers such that the number average molecular weight of compound (S11) is from 300 to 2000.

3. The crosslinked rubber article according to claim 1 or 2, wherein the crosslinked rubber article does not contain the compound (S1), or contains the compound (S1) and the total content of the compound (S1) is less than 100 ppb by mass relative to the crosslinked rubber article.

4. The crosslinked rubber article according to claim 1 or 2, wherein the crosslinked rubber further comprises a constituent unit based on at least one selected from the group consisting of perfluoro(alkyl vinyl ether), propylene, vinylidene fluoride, and hexafluoropropylene.

5. The crosslinked rubber article according to claim 1 or 2, wherein the crosslinked rubber further comprises a perfluoro(alkyl vinyl ether) based structural unit.

6. The crosslinked rubber article according to claim 1 or 2, wherein the crosslinked rubber has a crosslinked structure derived from hydrocarbon groups.

7. The crosslinked rubber article according to claim 5, wherein the crosslinked rubber has a crosslinked structure derived from a heterocycle.

8. The crosslinked rubber article according to claim 1 or 2, wherein the total content of metal elements is 50 ppm by mass or less relative to the crosslinked rubber article.

9. A crosslinked rubber article according to claim 1 or 2, used as a component for semiconductor manufacturing equipment.

10. A solid composition containing a fluorine-containing elastomer having a structural unit based on tetrafluoroethylene and at least one selected from the group consisting of a bromine atom, an iodine atom, and a cyano group, wherein the solid composition does not contain any of the compounds represented by formula (S1), formula (S2), formula (S3), formula (S4), formula (S5), formula (S6), formula (S7), formula (S8), formula (S9), and formula (S10), or contains at least one selected from the group consisting of the compounds (S1) to (S10), and the total content of the compounds (S1) to (S10) is 10,000 ppb by mass or less relative to the solid composition. A solid composition that does not contain the compound (S1), or contains the compound (S1) and the total content of the compound (S1) is 1000 ppb by mass or less relative to the solid composition, and does not contain the compound (S11) represented by formula (S11), or contains the compound (S11) and the total content of the compound (S11) is 1000 ppb by mass or less relative to the solid composition. H(CF ２ ) ｐ１ COOM １ (S1) H(CF ２ ) ｐ２ SO ３ M ２ (S2) F(CF) ２ ) ｐ３ COOM ３ (S3) F(CF) ２ ) ｐ４ SO ３ M ４ (S4) X ５１ (CF ２ ) ｐ５ (OCF ２ CF ２ CF ２ ) ｑ５ OCF(X ５２ ) CF ２ COOM ５ (S5) X ６１ (CF ２ ) ｐ６ (OCF(X ６２ ) CF(X ６３ )) ｑ６ OCF(X ６４ ) COOM ６ (S6) X ７１ (CF ２ ) ｐ７ CF(X ７２ ) (OCF(X ７３ ) CF(X ７４ )) ｑ７ OCF(X ７５ ) COOM ７ (S7) X １０１ CF ２ (OCF ２ CF ２ ) ｑ１０ (OCF ２ ) ｒ１０ X １０２ (S10) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In formulas (S1) to (S11), M １ ~M ９ Each is independently a hydrogen atom, Na, K, or NH ４ X ５１ , X ６１ , X ７１ , X ８１ , X ８２ , X ９１ , and X ９２ Each of these is independently a hydrogen atom, a fluorine atom, or a chlorine atom, and X １０１ and X １０２ Each of these is independently a hydrogen atom, a fluorine atom, a COOH group, or a chlorine atom, and X １０１ and X １０２ At least one of them is COOH, X ５２ , X ６２ ~X ６４ , and X ７２ ~X ７５ Each of these is independently a hydrogen atom, a fluorine atom, or a perfluoroalkyl group having 1 to 3 carbon atoms, and Rf ８ ~Rf ９ Each of these is independently a fluorine-containing alkylene group having 1 to 20 carbon atoms, and X １１１ and X １１２ Each is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms, p1 and p3 are independently integers from 3 to 13, p2 and p4 are independently integers from 4 to 10, p5 to p7 are independently integers from 1 to 10, q5 to q7 are independently integers from 0 to 3, q8 to q9 are independently integers from 1 to 20, n8 to n9 are independently integers from 1 to 30, and q8 and n8 are the CF contained in compound (S8). ２ A combination of integers such that the number of elements is 30 or less, where q9 and n9 are the CFs of the compound (S9). ２ The integer combinations are such that the number of groups is 30 or less, where q10, r10, q11, and r11 are each independent integers of 0 or greater, where q10 and r10 are integer combinations such that the number average molecular weight of compound (S10) is between 300 and 2000, and q11 and r11 are integer combinations such that the number average molecular weight of compound (S11) is between 300 and 2000.

11. A solid composition containing a fluorine-containing elastomer having a structural unit based on tetrafluoroethylene and at least one selected from the group consisting of bromine atoms, iodine atoms, and cyano groups, wherein one or more CF ２ It has a group and one or more ionic functional groups, wherein the ionic functional groups are COOM, SO ３ M, PO ４ M, or SO ４ M is a hydrogen atom, Na, K, or NH ４ The CF per ionic functional group ２ When compound (B) is defined as a compound having 30 or fewer groups, lacking carbon-carbon double bonds and carbon-carbon triple bonds, and having a number-average molecular weight of 3000 or less, the solid composition either does not contain compound (B), or contains compound (B) with a total content of compound (B) of 10000 ppb by mass or less relative to the solid composition, either does not contain compound (S1) represented by formula (S1) among the compounds (B), or contains compound (S1) with a total content of compound (S1) of 1000 ppb by mass or less relative to the solid composition, and does not contain compound (S11) represented by formula (S11), which is a compound other than compound (B), or contains compound (S11) with a total content of compound (S11) of 1000 ppm by mass or less relative to the solid composition. ２ ) ｐ１ COOM １ (S1) CF ３ (OCFX １１１ ) ｑ１１ (OCFX １１２ ) ｒ１１ OCF ３ (S11) In equations (S1) and (S11), M １ is a hydrogen atom, Na, K, or NH ４ X １１１ and X １１２ Each of the following is independently a hydrogen atom, a fluorine atom, a chlorine atom, or a fluorine-containing alkyl group having 1 to 20 carbon atoms; p1 is an integer from 3 to 13; q11 and r11 are independently integers of 0 or more; and q11 and r11 are a combination of integers such that the number-average molecular weight of the compound (S11) is between 300 and 2000.

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